Getting into graphic design

So I used to sketch and paint a lot and I got pretty good but I never really liked it that much so I abandoned that hobby after 2-3 years of trying to convince myself that it was fun (I do that a lot). 

I was asked to design some logos and posters for a show at our local high school and I found it really fun. I want to design some more stuff but I have no clue what. Any ideas?