First off what color do you want to paint? Lets take red for instance.
With red i would primer white. Then i would thin my red to about 1 part water to 2 parts red and just apply thinly but cover the mini. Then i would apply badab black wash from citadels line to cover the mini. After that dries and it takes a bit longer then paint to try say 4x longer. you also wana make sure its dry or it will mess up what your painting. Next you want to dry brush... trick is the brush needs to be dry < i know thats a crazy concept right, but i convince myself from time to time i can get away with a wet brush and i fail >. You dip the tip of the brush into the paint i used a flat about a quarter inch thick. then i brush back and forth on a napkin, when i know its ready for the mini i'll run it on my finger and if it brings out just my finger print i know its rdy for the mini. you want to do quick brush strokes back and forth. keep layering the paint on the brush and making sure it isn't thick. what your goal is, is to only put little bits of paint on at a time so it doesn't fill the detail. It really shouldnt take all that long per mini. after thats done fill in the detail, shoulder pads weapons boltgun metal colors and you should end up with something like this.

These blood angels are a bit rough because the camera takes such good pictures.

For these death guard my steps where.
Primer white.
Devlan mud wash.
Drybrush white.
Paint shoulders green.
Devlan mud wash shoulders.
Drybrush yellow on shoulders.
Paint weapon boltgun.
Mix a rust color apply to weapon.
Drybrush boltgun to leave recesses rusty.
Paint horns brown.
Done.
Hope this helps, sorry it's all jumbled.
Blind-