Hire an accountant and solicitor
pay off all debts (student loans)
pay of debts of family and friends and ensure certain ones had extra dosh to use
donate some monies to certain charities
Buy small properties in several different countries - venezuala, australia, uk, amsterdam, thailand, japan, vancouver, utah.
get an investment portfolio
finish school
open a small lgbt spas in three countries
open a women's retreat charity - where women with little or no money can come for a little holiday for 3-5 days with healthy food and relaxing, quiet, care.
Open a healthfood cafe, spa, tattoo studio where I'd be spending most of my time - with an artist's community centre for gigs/spoken word/gallery.
300 million is a lot. and there is a lot I can do with it.
Mostly I'd want to travel between my houses and businesses.
Maybe occationally hire a nice butch gigolo.
Or maybe have a few butches with business investment ventures they want to start that are also attractive and we get along... I could be a sugar momma. Have some pleasant, friendly entertaining, fun company in exchange for silent, hands off investments into their dream business.
I get to help some people out and get good company and a little fun now and again

for us both.
I dunno, single and stinking wealthy might suit me.