Lots of answers…
I think best is physical (checked: good for you)
next is professional- shop around, not always a clear RIGHT answer.
Secondly a curb has its place, if YOU (general you there not OP specifically) know how to properly use it. Suggesting to just use it blindly is silly. Suggesting a snaffle is all that it takes blindly is just silly.
My stallion can be very headstrong when he wants, even for a little guy so he isn’t a raging whore if you will, but he braces very badly- inverts and its just like a 50 lb weight on my hands.
So I rode with a mullen mouth low port pelham on trails and snaffle in the arena. Fine dandy it was sooooo much easier. But I rode double reins and had been educated to ride a curbed bit with two reins and it was lovely. Soooo much less fighting.
I have been taking dressage lessons and switched from a ‘western’ style to a full dressage bridle and OMG what a difference a basic noseband makes. Its not cranked, I can fit a finger in all the way around at minimum (in all the ‘tight’ places), he still gaps, and will still invert and try to run away but it isn’t nearly as bad… And let me tell you, I switched back to another bridle w/ no nose band and HOLY S%%T. It was a different animal.
I now have down graded to almost exclusively a snaffle even with my trail riding, but if I feel the need have no problem switching back to the pelhem… loved the feel loved the reaction, but not ‘proper’ training for dressage so I try to stick with that as best I can.
=) I wish you the best of luck though, it takes patience regardless of the route you seek, which bare in mind may not always be the last one… 