They are pretty easy to use, just use a little rudder with your stick to keep turns coordinated. If you see the little round ball off to one side or the other
think of it as a ball you can kick, if the ball is to the left kick it back to center with the left rudder and same if ball is to the right kick it back to center with
right rudder. It takes very small rudder movements to keep the ball centered.
For the most part, doing your flying to and from the fight, I would not put much worrying into "keeping the ball centered"........ "coordinated turns"
it will not affect you all that much, and even with most turns you will not need to use hardly any Rudder Input, if any at all
Also, when in a DogFight you will find times where opposite Rudder ( or Uncoordinated flight ), will help you just as much at times....... I am not saying using Coordinated Rudder does not help, it does.........
just a little self test you can do and see for yourself....... load up Aces high in the offline mode. go pick yourself the P51D plane and take off.......
ok watch the Stick & Ball gauge ( is in center of gauge cluster/cockpit dash )....... now get your speed up ( you can use Combat Trim ie... Ctrl X, or you can manual Trim....doesn't matter )
now with speed up, say 250 IAS to 350 IAS make some turns to the left... watch the ball slip toward the left side...
now do the same towards the right, make some right hand turns..... again watch the ball most times slip toward the left. only "quick, hard pulling, abrupt turns"... will you see the ball move sharply to the left and/or to the right....sometimes.....
Learning to use your Rudder ( pedals or Twisty Stick setup ) is going to help you, no doubt....... and will let you explore even more areas of the game... but unless you're flying formation, acrobatics, commercial aviation carrying passengers
..
you do not have to keep a constant check on "Sticking the Ball"........
don't get caught with your head stuck in your cockpit just saying
edit: for proper naming purposes ... Stick & Ball gauge I mentioned, refers to the Slip Indicator my apologies for using slang