Shoot the other team and shoot your own team.
1: Double jump and strafe and press every key that relates to movement, but keep your mouse on the target.
2: Aim for the feet, your shotgun is awesome, use it
3: WM1, and if necessary, strafe
4: Don't use targe, stickies are so much more useful 95% of the time. Lead your targets and don't rely heavily on your grenade launcher until you get good with it.
5: WM1, always keep an eye behind you for spies, don't let snipers catch you while you are using your minigun
6: Make a base that is has little to no out of range areas that soldiers and demomen can attack it.
7: Heal your team, don't heal spies. Your blustanger needle gun is incredible and can take down and scout with ease.
8: Aim for the person and shoot, body shots are still kills so don't feel like headshots are required
9: Don't be stupid. Never disguise as a scout unless you know what you're doing. Sometimes I'll disguise as scout just for the extra speed. Also your revolver deals 50-60 damage at close range. Use it.