Sensitivity: Windows 6/11, no acceleration, In-game 1.5 - 3.5, 400 DPI
If your DPI is different you can adjust in game sens to match it.

Settings: Highly depends on your computer, the goal is to have high FPS so adjust settings accordingly.

Tutorials: Watch stuff from the end of 2013 onwards, the rest will be outdated.

Deathmatch/Aim Maps: Go to browse community servers, type in deathmatch or aim depending on what you want, and filter the maps so you only see the ones you have good ping on and add those to favorites.

Adren Tutorials
War Owl Tutorials