what are the best muscles to work on for next football season, I play linebacker and long-snapper?

The REAL answer is "All of them"

Overall strength will serve you well at any position, in any sport.

Isolating a certain muscle group is just cheating yourself the opportunity to improve your entire game. Trunk muscles for endurance, leg muscles for speed and quickness, arms for powerful blocking and tackling.

Ask any high level athlete and they will tell you an overall routine is healthiest..

Good luck and be strong.

your arms are very impotant so you can make the tackle so do some pushup, lift weights, and do it to you think you need to stop,

then comes running you should run about 1 mile everyday and in about a month i would switch to 2 and then i a month switch to 3 and so on and so on but don't go pass 5

You always want to be strong in the lower body, so start running at least half a mile a day if your not already. Your arms are very important too

stick with the core lifts

deadlifts

squats

bench

clean

and secondary lifts too to help supplement those lifts. dont just ignore sum of the lifts and concentrate on others. wrking everything will also help u gain more weight faster!!!

upper body general strengthening and try backpacking with a heavy back back on hills and stuff for stronger legs

arm