One of the main concerns of controlling your Sim would have to be needs management.  There are eight needs that motivate your Sim.  These are Hunger, Comfort, Hygiene, Bladder, Energy, Fun, Social, and Room.

Needs are monitored by bars in your Universal Control Panel at the bottom of the screen.  Needs that are fully satisfied will be full and bright green. As the needs drop so will the bar meter, turning a paler green, then grey, until only the red side of the bar remains. Needs showing bright red in their bar need attention immediately!

The needs' overall score will affect your sim's mood rating, shown to the left and right of your character icon in the bottom center of the screen.  The perfect happy sim is 5 green bars, and a sim on the brink of death will have 4 or 5 red bars.  Once your overall mood drops below one green bar and into the red, your sim will refuse to cooperate, particularly with moneymaking or skilling, until his/her/its needs are dealt with.  See the end of this document for information on how this is different in the free will city of Betaville.

while you will normally need to deal with most of taking care of your sim's needs, some needs can be affected, positively or negatively, by interactions with/from other players.  Read here for more information on interactions.

Although by simply checking your 'needs box' you can see exactly what your sim requires, when desperation sets in, your sim will wave at you to try and get your attention, and an 'alert' bubble will flash above their head informing you that there really, really is a need.  It is always best to deal with your needs before your sim gets to this stage, as when your needs are red, your unlocked skills will begin to decay at a faster rate. As long are you are on a property (your own or someone else's), your needs will be affected.  Different property categories have different rates of need drop.  Time, as well as actions, will cause your need levels to drop.  Should you need to step away for a bit and you don't want your needs to fall while you're gone, simply leave the lot.  Your needs will not be affected while you are on the city view screen.

Although "Needs" and "Motives" are the official synonymous names for your sim's requirements, the term "Greening" has become very popular in-game to represent dealing with your sim's requirements - the term coming from the act of your needs bars turning "green" as they go up.  You will often hear "I need to green" or something similar in-game, and it is not unknown for human players behind the sims to use this term in real life, much to the amusement or bewilderment of those around them.

Eat something!

If you own - or are a roommate - at a property, you can make yourself food using the refrigerator.  The higher your cooking skill is, the more filling the food you make will be.  The quality of items used in food preparation will also affect the overall quality of the meal, and hence its hunger quenching value. Even the simple use of a food processor rather than preparing by hand, and using a stove instead of a microwave, can make a lot of difference - especially for a roommate with lower cooking skills.

If you are a guest at someone else's property, you will need to rely on them to provide access to food for you.  This could be by setting up a buffet table, by making group meals, or by providing vending machines on their properties.

Be aware: Neglect your Sim's hunger too long, and your Sim could die of starvation!

Sit, sleep, nap, or take a bath. Generally, the more expensive the item is that you are using, the faster it will raise your comfort level.  Sure, you could nap on a love seat and you might get a little comfort.  But if you're looking to really be comfortable - and fast - you may want to seek out an actual bed. Also, Sims find baths very relaxing, which makes taking baths a very good way to raise your comfort level.  A comfortable chair, and a foot massage from one of the crafted foot massagers, is an excellent way to bring this right up quickly.

Shower, bathe, brush your teeth, or wash your hands.

Even the prissiest of Sims starts to get a little stinky after too much working and playing.  Showering and taking baths are the most complete way to clean your Sim up.  For a quick "pick me up", try washing your hands in a sink or brushing your teeth at a medicine cabinet mirror.  These take less time, but also don't raise your hygiene meter to its fullest.

Take your Sim to the restroom! Get your Sim to a toilet when you see this meter getting low or you could end up with a very embarrassed Sim! Again, more expensive toilets get the job done faster, but if you're at someone else's lot, you just use what you can get.  Don't forget to flush!  Some toilets auto-flush, but most don't.  If too many Sims fail to flush the toilet, it can clog up, and you or the lot owner could end up with a rather yucky mess to clean up.

Sleep, nap, or drink coffee.

You work your Sim hard; you play your Sim hard.  It's time to give your Sim some much needed rest.  When your Sim's energy meter gets low you need to let them rest, and of course sleep is the best thing you can do.  Beds - especially expensive ones - work best for this, but you can also nap on couches or in chairs that recline.  If your Sim is not quite ready to slow down, you can get a quick energy boost by drinking an espresso coffee. Watch your bladder meter when you do this though, coffee will make that meter decrease quickly!

If you do not deal with your sim's energy requirements, they will simply pass out on the floor where they are, and stay there unresponsive for a little while until they recover enough to wake up.  If your sim passes out from exhaustion, be sure to wake him or her up as soon as possible and guide them gently to the nearest bed - or she will pass out again.

Entertain or be entertained! Sims just wanna have fun!  There are many objects in the game that can increase your Sim's fun meter.  Try dancing, watching TV, bashing a piñata, swimming, sitting in a spa, listening to music, playing pool, interacting with other Sims, even watching the fish in the fish tank.  The possibilities are too numerous to list; it shouldn't be hard for you to find something with which to entertain your Sim.  Here, I am "playing games" on a computer to replenish my fun bar.  The higher quality the computer, the higher the '+fun' gain.

Be sociable!

Your social need can be raised simply by being on a lot with multiple other Sims.  If you are a little more impatient than that, and wish to raise your social meter faster, you will need to interact with other Sims.  Clicking on another Sim will bring up different options to perform on or with that Sim.  Some you will just do automatically, "Talk to", "Wave" and "Salute".  Other interactions will need to be accepted or declined by the Sim you are trying to interact with: "Dance", "Hug", etc.  Social can also be raised by taking part in group activities:  Basketball, Chess, Swimming, and Pool are some of your options.  Information on interactions and their greening values can be found here.

You can also gain some social by interacting with pets, and although this is a slower method than by interacting with another sim, it is useful if you are 'home alone'.

How much does your Sim like the environment around them?

There are two ways that the Room score can be affected - primarily by the design of the lot, but also by its overall condition of care - or neglect.

When building your own business or home the room need is very important to keep in mind.  Sims like to be surrounded by nice things with lots of light, as well as lots of room to move around.  Rooms can be spruced up with artwork, plants, and even some of the more expensive furniture items can add to the room rating.  Look at the 'details' tab of any item to see how it affects the various individual needs - the crafted coffee table shown here has a room score of +10, meaning it is a very desirable item to have in your home.  Don't just stick with the bare minimum practical.  Decorate and make it look like a home. It's the little touches that make all the difference - but don't fall foul of object and property limits!

Dead plants, trash, dirty dishes, spilled water from the shower, and other messes will drop a rooms rating regardless of how nicely the room is decorated - so either hire the maid, or clean up after yourself!  When an item breaks, this can also affect the room score.  As a general rule, the higher the cost of the item, the more it will negatively affect the room score.  Something such as a piano or crafted item can be enough to bring the room from full green to full red in a second.  If it is during the working day (10am - 6pm sim time) you can call the repair man, or at any time call upon a friend or roomie with high Mech skills to come and fix the offending item.

Room score affects everyone in that room (although it will not affect anything outside of the walls surrounding the item - a good reason not to build "open plan").  If, by something breaking, the room score is very red, then everyone's needs will deplete faster, and if someone's mood is pushed below the 'green' level by this, then they will stop what they were doing and refuse to do anything else.

The following table illustrates the effect letting a need drop too low will have on your sim:

In the free will city of Betaville, there are two significant change in the above.

Firstly, sims will not use the shower or toilet while another sim is in the same room.  This 'modesty' feature can easily be overcome by designing individual restrooms rather than the common 'open' style.

Secondly, depending on the setting of 'free will' that you have chosen, sims will generally take care of their own needs if you do not - although not always the way you'd actually like them to.