Training

• For strength training I would look at Eric Cressey's work. He has tons of free articles. Focus on building leg strength primarily, with focus on rotational power also. For velocity work, I would check out anything done by Driveline baseball or Texas Baseball Ranch. I know Driveline has a free ebook on their website. You do have to have the set of weighted baseballs and plyocare balls though. If not, my suggestion would be to long toss and build your arm strength.

Another vote for Cressey... although it's too bad it's quite expensive to get a real program if you cannot afford a training program. It's a lot of core work and lean muscle building. In Jr/Sr year my son's velo went up noticeably. Perhaps that cruising high 70/low 80 when he started.  Don't think you'll add 15-20MPH with workouts only - there's some mechanics work that'll be necessary as well.  BTW: If you're a PO, as long as you have the fundamentals of PFP's, your 60 time probably don't matter ;-) as it's not 60 yards from mound to first!

+1 for JohnF

Need a lot of core work and don't neglect your foundation (the legs).  And along with strengthening the core, have a routine that includes some long toss.  Typically, mechanics is a big issue.  Analyze some video of yourself and compare it to what you can see in video of MLB pitchers, then note how they get "separation" (the rotational angle difference between their hips and shoulders) and how they lead with their butt as they start their move toward home plate.  Try to emulate those parts of their mechanics.

I agree with the other posters.  

I would add that core work needs to have a big element of rotational power to them.  

Doing a "six pack" abs workout or endless crunches won't do a ton for you.  A modified russian twist, Pallof presses, med ball throws, these are much more effective in developing rotational power for throwers.  

Others have thrown out some good names and programs. I would poke around on their websites and Youtube channels. You might have to invest in some materials like Jbands, weighted balls, plyocare balls, medicine balls, etc. but it is a small investment compared to the cost of ongoing training programs. Most of these places sell the materials on their website, but you may be able to find them cheaper at a sporting good store (i.e. Dick's, Sports Authority - ask you mom for coupons!). Over 90% of the content on Driveline's website is free. Also check Jaeger Sports for band exercises. A little research and you should be able to develop a nice routine.

Good luck!