We've all done it. Played with the 'primer army'. You get a new unit assembled and want to play it to see if it was actually worth buying. As much as I try not to, I usually end up with a unit or two that's not painted on table. Even the tournament standard of three-colors is a thorn in side of some players. You spent hours painting your whole army up only to have your opponent show up with glue still drying on his units. I played my fully painted AND based Skaven army of 200+ models in a recent game. My opponent had one unit that was primed.
You don't have to be a great artist to get three basic colors on a model. There's a lot of quick, easy ways to paint up models to at least give them a little flavor on the board. You can go for a quick white primer coat, wash, then drybrush. Dipping is another quick and popular method. I don't understand why people dump on dipping so much. It's quick and easy, and if prepared right, can give you some cool results.
I like to play with painted models but not the bare minimum. Everyone's skill is at a different level but there's a lot of ways to pump your painting. Practice is always the best, but challenging yourself is even better. If you got a local GW, ask about painting competitions. They're a great way to learn new tricks and get pointers on your technique.
Blogs are another great way. There's a ton of really good resource material out there. My current favorite is a blog called The Painting Corps. The guys there are incredibly talented and track down good tutorials from all over.
Massive Voodoo is another site I go to often. I think they're German but also have some of the best sculpts and painting I've ever seen. They're tutorials are pretty easy to follow too. I've been using their priming technique for my Lizardmen with some decent results. Massive Voodoo also has articles on art theory in the event you're inclined towards the heavy artsy side.
Painting by Tinweasel: good work, decent tutorials. A little sparse on the progress photos but cool results.
The other resource I use is Cool Mini or Not. You want to see what a cool Vampire Counts or Empire army looks like, go check it out. Its a great place to get new ideas on old armies.
Those are my favorites. Let me know if you have anything that you use regularly to help amp your skills. Books, websites, other people. I love learning a new technique so if you got something cool, let me know. Once I get my new camera, I'll some progress shots of my own stuff up. Until then, be seeing ya.