I'd tell her not to take other peoples' advice as higher than my own intuition when it comes to "not being brave" and forcing myself to talk to my crushes (or other people I don't want to talk to). "If you don't wanna talk to them, there is a good reason. That is your subconscious telling you that it's pointless in the long run and will just give you fruitlessly awkward memories that last for 10 plus years." >.<
Oh, and I'd say "don't ride your bike no-handed in a figure 8 shape on that one street with the curbs....you'll wind up hitting the curb and get a bad bruise in an embarrassing area."
Although in reality...I'm not sure I'd want to interfere too much with my past self. It could mess with nature and make my current life freakishly different.
maybe I'd stick with something simple and tell her not to worry.