This excludes the philosophical minefield that is clothes-folding. Please look that up and see what there is out there!
Contrary to popular fiction, you can actually put all your clothes together to wash! In order to do this, a bit of preparation is needed. By preparing your laundry, you remove the need to have multiple washes. Let's streamline things a bit.
Set any fabric dye: To make sure that none of the clothes stain the others, soak new clothes in a smallish amount of water and see if any of the colour runs off. If it does, try applying some vinegar and salt to it to set the dye. After about a few hours or so, wash with some soap by hand, and test again. After that, if it passes the test, you can wash it with everything else!
Check for dryclean-only: usually this means things made from very precious fabrics, or things made from very thick fabrics. You will find this information on your clothestags. Set these items aside for a visit to the drycleaners'.
Good! Now you have a bundle of fabrics that can be washed the same way, altogether.
In general, handwashing is easy! Simply put your clothes in a basin, add some water, and add some laundry detergent to the whole mix.
With the laundry and the detergent water in the basin, squish the clothes roughly! If you're using a bathtub, feel free to use your feet to stamp the water through your clothes.
If your clothes are a lot dirtier than usual, let everything soak for a while.
Now, if you're happy with the whole lot, drain the detergent water out and try to squeeze some of it from the wet clothes.
Add some clean water and squish your clothes in them again! Rinse until everything is soapless. Drain the rinsing water away and...
Ta-daa! You have washed your clothes!!!!!
Having clean clothes is a nice thing! Now, to make them dry and presentable, we'll have to use some hangers and the weather to help.
Some people have really complicated rules for drying and weather-watching and all that, but as long as it isn't raining while your clothes are drying outside (and getting drenched extra with rainwater), your clothes will eventually end up dry and smelling decent. Sunny days help, and you'll find that nice sun-hugged smell on your clothes after you've left them out. But leaving them out to dry on warm nights can work as well.
To get the most out of your drying, use hangers, and straighten your wet clothes on them before hanging them out to dry (make sure you have a place to hook your hanger onto to make things easier!). Use the side-seams of t-shirts, or the edges of pants or skirts to help you. This way, you'll smooth out any wrinkles that are there, and if possible, make it such that you won't have to iron your clothes at all!
Once done, hang to dry.
[A] If you have a washing machine: yay! You can get the machine to help you with the washing. Here's a basic guide to machine-washing settings:
If you need to, however, don't be afraid to use hot hot water if your clothes are extra soiled, or a high spin speed if you're tight on time.
When you're free, however, try to rinse the washing machine out a bit with either detergent or some antiseptic solution (sometimes leavings get stuck inside!). Once you've poured and run the drum-mechanism through some washing water, drain it; most machines should have an outlet somewhere that will let any residual water out from the drum.
(Even if you don't have a dryer or want to use one, putting in some laundry balls while the laundry washes will help to pull and fluff out laundry as it washes in the machine.)
[B] If you have a dryer/drying-capable washing machine: yay! Extra yay! You can use this to get clothes that are next-to-ironed without having to iron them.
If your clothes still have creases on them, or if you have a serious business outfit you need pressed and have no alternative, here are some tips:
Generally, the idea is to loosen any kinks in the weave by allowing steam to press through the fibrestrands, and to set them with heat. After this, you're home free to do whatever you have to to store your clothes!