How do you keep your hat on during a run without using a stampede string?  My hat is tight, but still blows off.  

Hat shape is more than a look or size.  You need to make sure that it truely fits ... oval, long oval and such.  Best to go to a hat maker and find out what is the right fit.  Many go by the size, but there is more to it than that and most western shops don't know hot to properly fit a hat.

I just pull the back part of the sweat band down and then put it on.  Works wonders.

As stated above--go somewhere that knows how to properly fit a cowboy hat.  

When I rope, I shove my mine so that the crown kind of "pops" out a little on the top and my ears stick out, LOL.  It also help a ton with a straw if you have them add "cutter bumps" on the crown.

Oval, long oval, round is a real thing so make sure it is shaped to your head, then crown shape is big. The lower profile hats are hard to keep on no matter what where as the Minnick crown shape is deep enough to pull down low. I also tend to either braid my hair near the crown so I have something to stuff a bobby pin into once I put my hat on, funny how that extra little pin and the back of your hat band being pulled down makes such a big difference.

Bobby pins & spray your forehead with hair spray immediately before putting the hat on