When you're playing in Estate (team death match) at the beginning, if you start at the bottom of the map run to the right (where the other team snipes you). Run if you think you'll die.

Keep jumping and a tip - don't stop moving - if you do you'll die.

If the enemy see you don't worry they'll go to the back, instead look straight down to the hole thing.

After that look at the window, go to the left a bit (not to far just close to the left window) and make sure the enemies don't watch you or they will try it jump in.