New to StarCraft II: Ask the Veterans
None of us were born experts—even professional gamers had to start somewhere. With the release of StarCraft II: Wings of Liberty, everything is new again and we're all discovering new strategies. This process may be easier for StarCraft veterans than for someone trying out their first RTS, so we’re asking our more experienced players to take a moment or two to share a few pearls of wisdom with all the newcomers entering this brave new world. The transition from beginner to veteran can be challenging, but with the community's help they’ll do just fine.
What’s your best advice for new players?

Also, to add in a little advice, although I'm not really a pro lol.
When I first got the game, all I wanted to do is KILL KILL KILL with tough units. But I've realized not to forget about support units. Using their abilities offensively and defensively helps immensely. If you get attacked late game by a large force that is clumped together, abilities like EMP, seeker missile, fungal growth, and psi storm can help soften them up tons for your normal troops.
http://www.youtube.com/watch?v=_EaRqeyfLSg
I just lost to void rays for the 1000000th time. I do not get how you are supposed to counter them when a Protoss player barracades himself into his base. I find by the time i have something that can sneak over his wall, he has too many of whatever he intends to spam (either void rays, or stalkers.) Or, worse yet, he attacks me first and by the time i fight him off, i have nothing left for his second attack.
If a Toss player is walling in and preparing to rush void rays, you need to build a sizeable ground force and hit them with transports. A reaper, or even speedling rush will fail if they wall in first properly. Transports behind their lines is key. If the fight does come down to beating the void rays you need : marines/vikings, infestors w/ nueral parasite or at least fungal growth and hydra/queen/muta support, or an equal number of your own rays and/or blinking stalkers to run away after their beams are charged, make them cool down is the key. Isolated turrets also work well because they have to fly to the next building after killing it, making their charged beam fade off. you just gotta swarm em!
Furthermore, don't be afraid to communicate in a team match. Some people get so intensely focused on microing and macroing efficiently that they tend to ignore the fact that there's another human trying to help them win. Two minds are always greater than one, and if you and your ally are on the same page, chances are you're going to do a lot better.
Learn your late game first, as that is where you will always have least experience.
Late game is where you will have the least experience because few games will go late game (i.e. 150 population +). It's good to have experience with this but you want the most experience in the part of the game you'll find most games are decided. Early to mid game.