Welcome to growing weed! It's fun and rewarding! There are plenty of folks on here to help ya along the way. How will you be feeding your plants? Do you want to grow organic smoke?

Couple things you should look at (common first grow screw ups):
Light leaks in your box. Temps. The more you can control your environment when growing indoors the better.
You will HAVE to use your timer when you switch to flower. I have seen a couple guys say they will just always turn on and turn off the lights manually. This is silly, life happens, weed naps etc