Jamescuk said:
Also use short burst, not long burst with the spray can, as it will save the amount you are useing
Heh, as well, "burst" in and of itself is generally not long, now is it

. Aside from saving the contents of the can, it's much more even. Think about it. If you held down the nozzle straight at it, it would pool and come out uneven. With short bursts and fluid movement, you cover every little bit of detail whilst preserving it.
Anyway, here's usually how I do it:
1- How should i go about using primer to prime my models? Should I spray a ceratain way, a certain number of times, in certain conditions?
Read above for proper movement and spraying. Usually you just want enough of a coat on there so that no grey is showing. As for conditions, the paint dries faster when it's warmer out. As well, why would you want to be outside if it's really damn cold out?
2- My first color or "basecoat." Do I PAINT IT ONE THIN LAYER, OR MULTIPLE THIN LAYERS, OR ONE THICK OR MULTIPLE THICK?
Multiple thin. That way, one, you preserve detail, and two, have total control over the amount of paint you put on the model. Who knows, maybe after two or three layers one model is satisfactory where it might take four or five to get another model done right. Human error.
3- any layers after the basecoat layer(s)...should they be painted in one thin layer, or multiple thin layers?
It really depends on what you're painting. For instance, you've basecoated a model with Dark Angels Green, but want to work up to a green inbetween say Dark Angels and Catachan. If that's the case (a horrible example, I know, but my mind is kind of shot right now), then as always, if one layer doesn't suffice, slap on another one.
4- How do i paint the model? Up and down strokes? Left to right? Soft? Hard?
Soft up and down strokes keep the paint even. The more pressure you put on the model while you're painting, especially plastic, in all likelyhood you could snap off little plastic bits or any glue work. As well, to my eyes anyway, up and down streaks, in the unfortunate cirumstance that they're there, are far less noticeable than those done left to right. It's the way the light catches it. If a light is shining down on the model, the left to right streaks act as light catchers, almost, and make them way more prominent.
5- This applies for GW PAINTS ONLY. What ratio of WATER TO PAINT to you use to thin?
I used to be dumb and have a little jar of water next to me, take the paint on the brush, stick it in the water for a bit to get a decent consistency, then apply to the model. Doesn't really work to well. I'd say for a full pot of paint, 1:5 ratio of water to paint. You don't want too much, otherwise you'll end up with a horrible substitute for ink. A good test I always use is add little amounts of water at a time, then shake the pot. If it sounds like it's moving around in there, but not too much (read: ink substitute), then it's about right. Again, you'll never, ever get an exact ratio for every paint, mostly because there's still human error involved, and the GW paints have different consistencies. Chaos Black is incredibly viscous and will require more water, whereas Skull White is quite chalky, so you want to add just a little bit to even it out. (Yes, I'm one of those people who adds the water in straight to the pot, then when I'm painting if it needs to be watered down more, I'll take care of it then and there.
6- How should the paint appear after it is painted on? slighty runny? really runny? stay in place?
You certainly want it to stay in place with gravity in mind. If it's runny, it'll drip down into places where you don't want it, potentially mixing with still wet paint or leaving streaks. Slightly runny I guess is okay in my experience because it's not too runny, the water helps to even out in the drying process. It can be a boon and a complete and total nightmare if you don't get it right, though.