I agree with the above -- packing too tightly is usually the main culprit. Also, if you're trying to avoid relights by puffing constantly, you defeat the purpose and smoke hot that way, too. So, yeah, pack lightly but get a good light to start. Try to err on packing TOO lightly and chances are you'll get it just about right.
Related to that, I find that a pipe with a more open draw (i.e., a bigger draft hole) especially through the stem can smoke much, much cooler than one you have to pull harder on. Moreover, a more easy draw requires a totally different mouth posture than the milkshake-style-draw. The wider the draw the closer it is to breathing and you can keep your tongue out of the line of fire better that way.
This is somewhat OT, but I almost always open up the stem of my new pipes with a needle file or tile saw "blade" (really a wire-shaped file). Rick Newcombe has written some articles on this practice and while I don't open my pipes as much as he does, most pipes benefit from a bigger draft hole -- especially through the stem.