samflamont:

First base is the cut off on a few of plays and they have to learn how to position themselves in order to keep the ball from getting away or taking bad hops off the mound.  First base is the cutoff man anytime there is a runner on second and there is a base hit to center or right field.  First base is also the cutoff man if there is a runner on first and third and there is a fly ball hit to center or right field as well (also, second and third depending how deep the ball is).  The cutoff from right has more to do with knowing the arm strength which we have already covered, but the cutoff from center field is the one that can be tricky.

How to position yourself to make the cutoff from center field:

First things first, once you see the ball is clearly a hit you have to bust your butt right behind the pitchers mound (if the pitcher is still there tell him to get behind home plate).  I have my players go to the second base side of the mound but I want their feet in the dirt.  If your feet are in the dirt, any ball as high or higher than your waist will clear the mound and therefore it will be safe to let go.  The mound is a tricky obstacle because if you let the ball hit it you have no idea where it will end up.  Also, this is a good position because it makes the center fielder let the ball go and not just throw it to the cutoff man but through it the cutoff man.

Go get the ball:

If you see the ball is not going to reach you, go get it in the air.  The one exception is if you are going to get a big hop you can let it bounce because chances are you will not get to this ball in time anyway and you will give yourself a bad hop.  If you see that you are going to get a short hop (the more you practice cutoffs and relays the better you will get at reading the ball) you need to take a few steps forward, catch it in the air, and then either make the throw home or take the appropriate action.  Also, any ball that is not going to clear the mound you must cut it off.  Even if the ball is online to the plate you have to cut it off.  The one exception to this is a fly ball where the runner is tagging up and nobody else is on base, you might as well let it go because nothing can be hurt from a poor throw or hop.  Remember to give your outfielder a target and be noticeable to them as well.  The most comfortable feeling as an outfielder is seeing the cutoff man and knowing right where to throw the ball.

Have fun, Play hard, and never stop learning.