18 Year Old Gap year?

I am Currently 17, and in High School looking at what I would like to do after I graduate I know, I would like to do a gap year, so I am really just questioning where its a good place to go as a Solo Traveler as an 18 year old. Is doing a gap year with a company such as Real Gap Experience. As well as in general trying to decide what I would like to do while on my gap year. I am thinking going to Australia, as it is my best option from a logistical stand point at the moment, with me doing some farm work. To try and help me fund the rest of my trip. I am looking for any and all recommendations from trip company to backpacks and gear to bring.