Masturbating?

I am 18 and I haven't really ever masturbated before. It's just something I've never really thought of doing. I have been sexually active for a couple months but I have never orgasmed before. My boyfriend gets frustrated because he can't make me cum. I want to start masturbating but I don't even know where to start. Do you guys have any tips or tricks? Should I invest in a vibrator or a dildo?