I'm actually impressed with your interest to go natural - the last thing I was trying to do at 15 was go against the grain and let my natural hair shine through. And, I say that only because I've gone to predominately white schools most of my life as well and was always indirectly taught that straight hair was just better. But at any rate, the one thing you definitely DO NOT want to do is flat iron, blow dry, or hot comb your hair straight while transitioning - it defeats the purpose.
When you apply heat to your hair you're essentially drying it out of all it's moisture and tripling your chances of heat damage (which, on permed hair, is transition suicide
All it takes is for the temperature to be a little too hot, or for you to have flat ironed your hair just a little too much for you to damage your new, growing natural curl pattern - hence heat damage - and have to go through the entire transition process again because it will still be just as dull and lifeless as ever. Some say that a healthy rule of thumb is to use a flat iron no more than once a month - but I say learn how to let go of the 'flat iron crutch' and do something different with your hair. The hardest part isn't waiting for your hair to grow but learning how to do your own hair when almost everything you're used to is a no-no.
No-No #1: a flat iron
What worked for me when i was transitioning was learning how to do a good braid out, twist out, and one i'm-almost-late-and-don't-have-time-to-think hairstyle. spruce it all up with a cute headband or flower clip, whatever works. and look up some styles on youtube (they made such a difference for me as far as inspiration and motivation).
And, of course, keep doing what your doing. Asking questions is the only way you'll get answers and it seems like you've gotten that much down already
If i could think of any last words of advice I'd say:
*do all the research you can on taking care of natural hair (because opinions differ, but you'll soon notice some advice that remains the same)
*concentrate on the health of your hair - trust me when i'll say that if you take good care of it then it will look it's best.
*take all setbacks in stride. you'll have bad hair days, or realize that you've been using the wrong conditioner this whole time - but forgive yourself and move on.
I wish i could think of more but I'm having a brain fart right about now.lol. I just had to respond once I saw your question.