Rick doesn't have time to say everything he would like to say in a DVD. To expand on the fingertip grip, use it if you can draw the bow with a relaxed hand without feeling like the string is going to slip off your fingers. It is much more important to draw the bow with a relaxed string hand than it is to draw with the string on your fingertips.
For example, with bows under 50#, I draw with the fingertip grip. With my normal hunting bow, which is 55#, I put the string in the first joint. With my 65# bow, which I don't shoot much anymore, I really get into a deep hook.
Check your string hand frequently that the back of your hand is flat and relaxed, to ensure that you aren't torqueing the bowstring.
You're not overbowed; your 50# bow will be fine for you. Everybody has trouble holding. Practice holding without firing the arrow. When you do fire the arrow, make it the most important thing you do in the shot until you get it mastered. In other words, promise yourself that even if the entire rest of the shot falls apart, you aren't going to release the arrow before you hold it for two seconds at full draw. Easy for me to say....