Well, you already made the first big mistake, which is growing weed in the first place.
But what's done is done. You'll make mistakes. Be prepared for that and don't panic when something happens or you don't know what to do next. Have low expectations on your first grow, and be thankful if you have anything at all to smoke.
Be patient. Plant time is different than human time. We can't work on our plants like we work on our cars. Research as much as you can before you do anything, try and find out more about plant botany and horticulture than "growing weed" perse. Basic plant knowledge will carry you much farther in your growing career. When you finally do decide on an action, wait at least 48 hours afterwards to observe the effect. You can really Fck up your plants second guessing your decisions and subjecting them through every "technique" known to man.
Why did I say growing weed was a mistake? Because if you're really new to growing anything, then you should start out with tomatoes first. They're very similar to weed and if you can grow a good tomato plant, you'll be able to grow cannabis just fine. I just think we're too emotionally/financially involved when we grow weed for the first time, and that is what causes most noobie mistakes. If I could do my first grow over, that's what I would do. You should still get some tomato seeds and grow them next to your weed just to have something to compare it to. Plus, a pack of seeds costs under $2.00, so you could do all your experiments on the tomatoes first if you're having doubts about whether something will work or not. Go buck wild with them and test out anything and everything. Just remember to keep a control plant as a standard.
Other than that, welcome to the forum and good growing!!