Let me see...
I think I'll divide it into school/career, lifestyle, and mental.
School/Career: You seem to be a pretty smart cookie? Well, now focus on better studying habits. You will more than likely hit walls going into first entering University and then your next level of education (with the second being harder). Also, try and get a few connections in the field you go into. (I did a bit for my undergrad, but I can do more). Invest in a good spell check and work on your grammar. Despite how many years of writing papers, making RPs for e-feds, and being complimented on my writing ability by some, I still suck ass at my grammar. Don't fear being wrong. I know you may not feel that way right now, but those doubts may come in.
Lifestyle: Get exercising and improve your eating habits. You are not the biggest athlete in the world, but try to find some physical activity you can do that you have fun with. Also, I know you are a picky eater, but start trying new foods. I've opened up a bit already for my diet, but keep going. Practice cooking. Eating out is expensive and while it may be easy when you are busy and grocery runs are expensive upfront, but eating out adds up a lot more. Spend more time with some loved ones. I know the internet is distracting, but you never know when they are gone.
Mental: You are an anxious little beaver, and at times that may spiral a bit into depression. Get counselling with it. Your feelings are valid, but having places to vent about stuff can help. Oh also... You know how occasionally you wonder what it would be like if you were a girl... and you like playing as female characters?
YOU'RE A WOMAN, DAMNIT! EMBRACE IT! EMBRACE IT!