The k98 is basically my default weapon. I'm not twitchy enough to use assault well, I stink with the support weapons. The k98 is very effective at range. Usually it's 1 shot, 1 kill. Tactics-wise, I tend to stay standing up and strafe back and forth around corners/cover or pop up and down behind cover. That way if I miss I'm behind cover as I reload. Also, if you stand still too long trying to aim you usually just end up dead. You can play sniper with IS as people have noted, but you'll lose against mg's and snipers most of the time.
On the other side, the M1, I'm not as good. I feel like I'm shooting rubber bullets most of the time. The problem is the damage it does. Unless you get a head-shot or perfect chest shot it's not likely your target is going down. The recoil is so much that lining up the next time takes almost as much time as the k98 reload. You can crouch or prone and reduce the recoil, but then you are immobile.
In the end, it's all about practice.
--Mr. Bildo