I'm a TF1 sniper. I haven't played in several years, but the idea is the same. My favorite map is Rock2, so I'll use that as an example.

Whoever said not to engage in sniper wars is missing the point. As long as you dominate the sniper nests, you can engage in the sniper wars, and defend your front door at the same time. Sniper wars are necessary to do this.

My technique in The Rock is to move up to the sniper nest until i'm tucked just behind the rocks to the side of the window. Then, I turn and aim at the rocks to the side of the water, then start charging. Then I slowly start to move to the right(or left, depending on what side you're on), turning slowly so the bead never hits the wall in front of me, and is not seen THROUGH the wall by any snipers in the nest opposite me. I also make it a point to double check for beads before I do this, as some newbie snipers never know to strafe the bead BELOW the window. When you're in position, be ready to move at an instant's notice. While you're charged, you can't move very fast, but it's better than nothing. Strafe-shooting is very fun. If you can't find anyone to shoot, move your bead in a triangle, from the top of the door to along the bottom edge of the window(s). Do NOT shine the bead through the window! Experienced snipers will pick up on this and know you're out there. The point of the triangle arrangement is to cover all the bases while you're zoomed in. You can also bind a key to a toggleable zoom function. The most basic is:

alias +zoom "fov 30; sensitivity 10"
alias -zoom "fov 90; sensitivity 15"
bind mouse# +zoom

This, when bound to a mouse button, will zoom to a field of view of 30 degrees and set the mouse sensitivity to 10. When the button is released, it goes back to 90 degrees and the sensitivity to 15. You can set the sensitivity to whatever you find comfortable. Using this enables you to zoom out while the rifle is charged. Very useful in a meelee, just charge the rifle and click the second button to disable the zoom.

Anyway, that's my favorite position in the rock, I do do the courtyard some times, but it's not nearly as satisfying.