I've started back learning to play (starting over from ground zero again) after a 50 year layoff. Now have the time and additional focus that I probably lacked as a young teanager. We'll see how that goes but darn it, I'm giving it my best shot this time. Been at it for a few weeks and remembered from my first go around, you have to pace yourself or you can really mess up your fingertips if you don't. Three 10 minute sessions with a break in between and rubbing the tips as you rest is more than enough to get a good start. One thing that has really helped build up my callusses is an old trick that I heard Eric Clapton swears by. Instead of vinigar, he uses rubbing alcohol, either dipping the tips of your fingers in a pool on a plate or dabbing with a cotton ball. Very cooling effect after practice and a quick drying effect that I'm sure is helping to toughen up my tips. Been working great for me! No blood blisters this time around.