I'd go for a nice set of Ray-Ban's mate. I've tried a lot of different sunglasses, some quite a bit more expensive than Ray-Ban's but they seem to be the best wearing and last the longest. Some models have nice thin arms as well, therefore you don't get a headache when you have them on all day with a headset.
As for the headset. You probably will want to invest in one sooner or later if you are planning on making a career out of this. I recommend the Bose or the new David Clark X11 (Helicopter version should be out later this year, or early next year). They are pretty pricey, but again if you are going to make a career out of this you will want something good and light if you can afford it.
Most of the other stuff really is pilot preference. I don't wear a kneeboard, just a clipboard or whatever I find lying around the cockpit that I can write on, however I do fly a aircraft with an auto pilot therefore not much need for one. If I remember though I did use one when I was in flight training.
I suppose if you want to look the part you could get gloves, a helmet and pair of goggles, oh and don't forget the scarf and leather jacket.
Hope this helps.