There were 3 things that really helped me improve (though of course I am still a newb too and have a long way to go):
1) Thin your paints (I use a mix now of 2 parts water, one part extender and one part varnish, though others use Future floor wax instead of the varnish). Everyone here seems to agree on this one.
2) Get some good brushes. Everyone says Winsor and Newton Series 7 are the best, and they last a long time if you take care of them (read: don\'t leave them sitting in your water!). I bought some and they really changed the way I paint, and they actually have lasted about as long as 10-15 of the cheapo golden taklon brushes that I was using before--so far! If you google the brand name and do some comparing, you should be able to get a 000 for under $9 American.
3) Read this website obsessively. There is so much information on this site that it is hard to absorb it all. Check it out, so you know what is there and go back to it when you are ready. If you get involved on the boards then people will be happy to give you feedback and tips, which will speed up the rate that your skill improves.
Oh, and I guess one more: keep practicing. Every mini that I have painted has been the best one that I have ever done. Practice, practice, practice
OK, one more. Make sure that your photos are clear and well lit so that people can see your work well enough to give you good feedback. There are a few articles on this site to help with that too.
So those are the three (ok 5) things that have helped me. So far I have not won any Golden Demons, but my friends are mightily impressed every time I pull out a new figure :flip::bouncy:
Hope this helps,
Michael