When you put on a girth, (call it a cinch and people may laugh or be confused – done that) you do it up on the right side first, then the left. For Mudpie (who bloats) I put it on the last hole and then after I get it on the other side, I go back and start adjusting it up, switching sides.
There are many different types of girths... you need an all purpose girth for a jumping saddle. Shaped leather girths like this
one, are my personal favorite. Fleece girths, like this
one, are also good, but if you live where there are "stickers" (burrs) and take them on a trail ride then you will have HECK getting them out! Your english girth should have elastic on one or both sides, and the buckles should have rollers. :)