I need some tips on pitching?

I play outfield and my middle infielders tell me when i throw the ball in for the cutoff it hurts their hands. There also telling me i should pick up pitching, ive done it a handful of times in the past but never really got much from it. I seem to throw a bit slower when on the mound and i cant really throw many offspeed pitches. Im looking for some advice because if i can get low 90s which ive been told then i need to learn some offspeed to be a productive pitcher.