Go more orcs than gobbos, unless you have A) no sense of tactics at all and B) you love utter chaos on the battlefield, weither you win or loose.
My Fiancee is building a Gobbo army, strictly because I play, she isnt the wargamer type. She has no idea what tactics are, let alone how to impliment them (ok, thats being sarcastic) But is happily painting her Gobbo Gliders and Squigs, waiting to unleash them on the field.
Gobbos = Chaotic funstuff
Orcs = Heavy shocktroops
Me, I prefer Darkelves because the game is easy to predict by the end of the second turn. They either completely dominate their opponent or the loose baaad. They are hard as hell to play properly (especially the army setup I play), but that just makes it all the more rewarding when a new opponent I have just beaten goes "Damn! I didnt think that would work!"
Advice to newbies in WH or 40k, play with strangers in a local hobby store (but not a GW store, they have full priced wares and are too busy trying to push too many titles to devote much time to the one you want to play), avoid playing the same friends over and over, that will just stagnate the game.
Also, if yuou know you and your friends will be playing, chip in to each others armies, and spend painting time together. It makes the game itself that much more fun, and keeps the tedium of the assembly/painting down.
Xhar
P.S. Buy the book/codex for your army FIRST, then build an army acording to your tactical taste and the availability of units set out by the book.