Compare new cards to old, similar cards. That's why constantly playing Limited is important.
Don't force a deck around pet cards that you like. Be willing to switch colors and ditch your first few picks if another strategy presents itself.
There is no substitute for practice. Use proxies or an online client to get reps in with a deck before you decide to invest in it.
Check out:
Magic: The Gathering Proxy Generator - Input the cards you need and the site will generate card images the perfect size to print, cut out and sleeve up.
Cockatrice - An online client to build decks and play against yourself to test things out.
Organize your board in a consistent way that makes sense to you. ie Creatures by power in descending order. Find something that works for you and be consistent.
Send and receive cards from everywhere! We also talked about how to tell if a card is fake.
LSV set reviews on Channel Fireball