99% of what's posted on YouTube about Glock pistols contains, at least, one or more errors. If you want to learn how to tear down a Glock properly, go here -
http://glockparts.com/Default.aspx?PAGE=Main Page
There's a cruciform on the rear of the trigger bar. Polish the back edge of this cruciform with a Q-Tip. (You can use a Dremel Tool on the rest of the lockwork if you want to; just be sure to work barehanded so you can keep track of heat buildup.)
Use a Q-Tip on the vertical striker lug, too. The bottom of the connector has an, 'L' shaped angle to it. Do absolutely nothing to change this angle. The Alpha Rubicon, 'Glock Polishing Instructions' are as good as any.
If you don't round the rear edge of the trigger bar's, 'cruciform sear plate', and leave the bottom of the striker lug alone, too, the principal cause of a Glock, 'doubling' will be eliminated. If you don't change the bottom angle on the connector, you'll eliminate the second most prevalent cause, too.
So, leave your principal contact edges nice 'n square and sharp, and don't change any of the lockwork's angles. You'll be fine.
What do you mean, 'I got the tools ...... ' The only tool you need (or should use) is a Glock Armorer's Tool - Which is simply a machinist's, 3/32 inch diameter, long-shank (1 1/2" +) drift punch. Sears and True Value Hardware, both, sell them. There's nothing on a Glock you can't takedown with one of these.
HINT: Work with your fingers on the very tip, NOT on the handle. This way you'll avoid scratching the gun. Wiggle the slide stop as you remove the #2 (trigger) pin.
Disassemble from left side to right side. Reassemble from right side to left side. Remove and replace all pins in exact numerical order: 1, 2, & 3 out. 1, 2, & 3 in. Make sure the trigger (return) spring is reinstalled in the shape of an, 'S' - Not a, 'Z'.