If you're new to this, I'd say to just go with the kit tracks as Shermans (and most of the US armor lot) had "live" track. There was no sag in the track which is what you see on a lot of Russian and German pieces. They have whats called "dead" track. (it's late so a good and proper explanation escapes me.) In general, individual track links (especially the metal ones) are less than ideal for depicting live track. Single length, or rubber band, tracks are most ideal. Rubber band tracks aren't the best medium for getting the most detail out but Tasca, AFV Club and the Dragon DS tracks are all very well detailed (I know I left out a few companies who also do rubber band tracks well but I just listed these 3 as points of reference). Plus now in many kits you get tracks that you can connect using regular plastic cement instead of having to melt little nubs.
Now the indy link tracks do usually have better detail than the rubber band tracks and are more well suited to depicting "dead" track but they are very tedious to make. You can use these tracks to depict live track too, don't get me wrong, but you then need to correct for sag by taking a link or more out or by adding one or more in if the run is too short. If you're going for the metal tracks they get to be expensive as well. Both options have their pros and cons and a lot of modelers have their own preferences.