PvC as in player vs. comp? Or is it something else? If it is then I'd say play the comp and save your replay. Review it for any mistake you can prevent from happening. Find a friend you can trust and play each other on the UMS form of LT so nobody gets a loss.
I'd strongly recomend you don't get used to the comp they play stupidly, but if your going to play them anyway use a Ladder map.
If you play USEast then I'll be happy to help your friend. I'm not the best player, but I can teach him the basics and some advanced stuff that can save him in most sittuations. I won't be a smart ass or a bitch about it either. I just like training and helping people on B.Net. My SN is TheOpoism. and the period is part of my name.
I can give you a run down of a few basics now:
1. Only 3-4 Workers per Extractor, unless far from your CC/Nexus/Hatch
2. Expanding can be a key to winning the game. The more resources you pour in the faster you can pace to.
3. Always scout (I don't do it alot on LT) but you should.
4. Always have detectors and spell casters, they will always be able to help.
5. Learn all hotkeys and practice micro.
6. When your sending an army to attack, use attack move instead of just clicking. Attack move can be done by hitting the A key before clicking or clicking on the attack icon at the bottom.
7. Set forces if you have alot of units.
8. Never underestimate anyone.
Some Protoss tips:
1. Always put a few spread out cannons all around your base.
2. Make sure you get a few Reavers and detectors.
3. Don't mass at all. A large mass of Carriers can be destroyed easy.
4. Be careful of Terran, they will most likely wall which can be bad for your Goons and Zealots. This is why you should practice micro.
5. Dark Swarm can be devastating with Lurkers, so you should always leave some Zealots or DT's around your base.
Hope these tips help. Theres way too many to put on this forum so I posted the few things that can be a key to winning.