This helped me a lot when i started playing sof long time ago, hope help other people.
1. allways aim for the head. 99% of all new players aim way to low. try to aim higher.
2. never reload in close combat, change gun instead
3. try to predict where the emeny will come and aim at that spot when you are running.
4. train to shoot at a spot at a wall and move side to side while keeping the aim at the same spot
5. make your own cfg file with the best settings for YOU. my jd cfg file is good for me but wont be good for you. find the keybinds that is best for your fingers.
6. try to spectrate some realy good players. I learned SO much by spectrating some good players. learn to move like they do. Try to go to http://www.clanbase.com/demolist.php?lid=1410&post=1and download some demoes. i learned ALOT just watching the last years finals from the national cups.
best regards