So I am far from being an expert, been doing this for just over 1 year, have about 11 batches under my belt, all extract partial boils. Over the course of my first year I have learned a tremendous amount from the people on this forum so the best piece of advice I can give you if you are new to homebrewing is to read and consume all of the knowledge you can from these boards.
Aside from that I have one other piece of wisdom to share...
Take a 6 pack of every brew you make, set it aside, and leave it alone for at least 8-12 months.
The hardest lesson to learn (though it is by far the most frequently given piece of advice from the gurus on this board) is patience. I can't fault any new brewer for ignoring this advice b/c I know first hand just how hard it is to resist the temptation to taste your latest creation. We seek all kinds of creative ways and reasons to avoid exercising the self control required to let your beer properly age and condition. And to be honest, I am not convinced that abstinence is the best policy. Tasting your beer early can be a very valuable learning experience, especially if you give yourself an opportunity to taste your beer after it has been properly aged and conditioned as a basis for comparison.
Two weeks ago I started chilling a few 6 packs from the first beers I made last year around this time (all of which were good then) and all I can say is WOW, it is absolutely amazing what time does for a homebrew, they are GREAT now! Had I known what I know now after tasting a few of these a year later, I would have set aside at least 12 or 24 from every batch and just brewed more often to make up for the difference.
Do yourself a favor, go ahead and dig into that 4-6 week old beer now but set aside a 6 pack and forget about it. You will thank me for it next year!
So I am raising this glass of my inaugural homebrew one year later to Revvy, Yooper, BierMuncher, Bobby_M, EdWort, yuri_rage, olllllo, and the many others on this forum that taught me the most valuable lesson in homebrewing...Patience.