In addition to the advice already offered, I would also recommend wearing ear plugs when you go on the highway. In addition to saving your hearing, the wind won't seem as strong if you can't hear it.
^^ yes, I found that this helped, also I think someone mentioned to check your tires and pressures. I too was a bit daunted when I first got my ninja 250. Keep riding , the more experience you get, the less unstable you will feel.
Also, you may want to get someone to check your steering head bearings just to be sure.