Honest answer? Too soon to know if my techniques are tricks or if they are luck. This is only my second year with my own real garden. I had two years prior to that with a few big pots with a tomato plant or two and some carrots. My Dad had a large garden when I was little that I followed him around through but I don't know how much I learned from that.
The only real thing I am confident is important is start the plants I previously mentioned inside, give them LOTS of light just inches above their leaves to get then nice and strong. If the light is too dim or too far away the plants grow tall, skinny and weak. When it comes time to move them outside, harden them off. I took two full weeks to harden them off. Start with a hour outside, protected from wind and too much heat and extend that little by little each day for a week or two. My tomatoes got zero sunburn.
Also for the tomatoes and peppers I pinch off all the buds for weeks. I won't start letting them set fruit for another couple weeks. They'll put more energy into growing strong roots and branches that way...a good foundation for better production.
All the other veggies? I don't do anything but sow the seeds, give them water and mulch (straw). And I've learned my lesson about keeping them protected from hail!
A good resource I've found are the videos on www.burpee.com