As someone who mains the Engie in TF2, I solemnly swear:

 

-Not to put a sentry in front of an enemy spawn. Spawn camping is for cowards at the best of times.

-Not to place a teleporter exit at the edge of a cliff.

-To remember that my primary job is to help my team. Dispenser heals before sentry kills.

-To not be afraid to move away from my sentry if it means helping to cap a point at a crucial moment.

-To get a teleporter up and running to help my teammates stop the cart.

-To not be afraid to go on the offensive. The front line starts wherever I put my sentry.

-To kill the spy before fixing the sapper (otherwise, they spy will totally just keep reapplying the sapper. If you kill him fast, you'll have time to fix things).

-To not be afraid to separate the dispenser from the sentry. The dispenser goes where the team needs it.

 

So shall it be written, so shall it be done. Now let's solve the problems with a little more gun.

Also:

 

Using a Level 3 Sentry gun in offense is sometimes way better than a Minisentry. A large gun can hold off territory gained by your team and will take significantly longer to take down than a Mini (or maybe a Demo will use up 5 stickies or a Medic pops uber to get it out.)

 

Sentry guns are disposable. Your life is worth more than the gun. Run away if a Demo or Soldier are about to be Ubered, and perhaps grab your dispenser in advance.

 

After setting up, you are not a slave to your gun. Walk around and scout out for people trying to flank, and try to trick them by guiding them into the open. Or just use a Widowmaker and pour all your metal into your enemy and laugh because infinite ammo is fun.

 

While these are just tips, it's something I follow instead of strictly going by the norm.

Edited October 18, 201510 yr by Tuna

Remember that your Rescue Ranger is your friend if you're playing offensive level 3 sentry's.

As a Demoman player only myself, I can give you this advice:

 

- Don't place your building on places Demomen can easily set Stickies, and watch you Engies ragequit

 

I've done this over and over, and I can't get enough of it