First time advice:
1. Use good soil. I recommend Fox Farm Ocean Forest. I flush with water 2 times the container size before adding the seedling because it's a little "hot" on the fertilizer. Then I don't use any nutes until 2 weeks have passed.
2. Get a good nutrient lineup. I use all the Fox Farm line, supplements and all.
3. Start off with 1/4 strength nutes, then go to 1/2, then 3/4. I don't even get to full strength until flowering.
4. Important: Only use nutes, every other watering.
5. Watch your pH levels, both watering and runoff after watering. Needs to be around 6.8. This was my biggest problem as a newbie. I let it get down to the high 5's and it caused lot's of problems.
6. Don't over water.
7. Don't under water.
There's more, but I didn't want to write a book right now.