I said this already, but to reiterate – the scout rush is effective, but if you die please, for your team’s sake, switch to a more powerful class (soldier, heavy, demoman) or something more useful (medic, engineer if you have less than 2), at least until you take the middle point.
After spawning (from your initial spawn) your team is given the option of going left or right. My instinct is for some reason to go left, but since it doesn’t really matter either way I’d encourage getting into the habit of going to the right, since you have better immediate access to the final control point and the conveyor belt route should you need it.
“But if it doesn’t matter, why does it matter?” you say. Well there’s also the matter of teleporters. It’s wasteful to place teleporter entrances at both the left and right exits of spawn, since they will have much more downtime (100% charge but not being used) than if they were all on the right exit and your whole team always went out the right exit. Although you may not be able to herd your teammates out the same door, at least try not to split up the teleporter entrances.
Speaking of teleporters, a good spot for a teleporter exit when attacking the middle control point is in the vent of the second control point building, the bit that drops out just outside the warehouse with the ramp. It’s difficult for enemies to destroy without going all the way around and provides very good access to the middle point. Of course if a spy gets to it, you have no chance of saving it, so it’s pretty much a once off spot.
After taking the first point, it’s alright to have a scout or two, and if you should go scout, there’s a couple of strategies that can pay off nicely at times. The more difficult one that is very hard to pull off is to leave the middle control point about 10 seconds before your team captures it, so you’re standing in the enemy’s second control point as soon as the middle is captured and you can start capturing straight away. Sometimes it will take the enemy longer to react than for you to capture, and you can take it by yourself, after which you can rush straight on to the final point and have a crack at that, or hang around at the point you just took and defend it for as long as you can, preserving your team’s massive spawn bonus. The cavalry should arrive shortly.
If the previous tactic is implausible in your situation, then as a scout (or any class really) an often undefended route to the control point is in through the enemy’s garage and up the stairs to the second floor. From the balcony you can fire down on the people below, especially targeting medics and engineer buildings, and not only kill them, but act as a distraction (effectively flanking them) taking some of the pressure of your teammates capturing the point.
When attacking the final point, make use of the new room Valve’s given you, on the second floor of the second last control point building next to the conveyor belt room, with the windows overlooking the area around the final control point. Taking possession of this room allows the attacking team to garrison snipers or soldiers in it to take care of enemy troops and sentry guns. Remember your priorities, i.e. medics and sentries first.