General Tips:
<^> Try not to kill any other people and stay to capturing the flag for the scout is weak and vulnerable.
<^> Outrun those sluggish, but powerful classes like that HWGuy and the Soldier. When you are further away from them the harder it will be for them to kill you.
<^> Remember that you have caltrops to use if you are being chased. But don't forget you don't have any trusty sticky gren (regular grens) to help .
<^> Use your concussion grenades to help you fly around. You will learn how below.
<^> USe alternate entrances to the enemy base. It might save your neck...
<^> It is possible to take out sentries and HWGuys. But needs some time. Just circle strafe around them while shooting your shotgun or nailgun.
<^> What ever you do, don't run in a straight line. The enemy snipers will shoot your head away.
Defensive Tips:
<^> Don't even bother...
Offensive Tips:
<^> Only capture the damn flag. If there is a sentry or anything tell someone like a demoman to destroy it.
<^> Use your speed to maneuver around people and keep running. Don't stop and take a drink.
<^> If possible tell some team mates to kill some defense for you before you get the flag.
<^> When you are inside the enemy base in the flag area and you see that the defense is to powerful and will run you down in 1 second flat, you should lay low and call for some backup.
<^> The opposing team will usually think that you are going to steal the flag. You can use this to distract them and let in a more powerful but slower class like a Soldier.
Techniques:
<^> CONCUSSION JUMP 101
To perform and successful concussion jump timing of the grenade is essential. It takes 3 seconds for an grenade to explode. First way to concussion jump is to hold the conc gren is your hands and count to 3 (one Mississippi etc...). Then on three or a bit before run off the bases roof or whatever and jump, if done correctly it will send you flying to the enemy roof. Second way. You must throw the grenade on the floor and stand on it. Then count to 3 and at 3 press jump and forward to send you flying away. I prefer the first way, I feel like peter pan or something.