Just decide wether you want to go weak hand over or under and place the shells accordingly.
For a combat reload I go under, so I place the shells in the saddle from the bottom. When I reach for one ill use my index finger to push the shell down while using my pinky to support the bottom of the brass. Once I have it flush with the top of the saddle I use my ring finger and thumb to pull it the rest of the way out.
I'll then hold the shell with my pinky and index finger while my middle finger and ring finger cradle it.
I stick my thumb straight out and I use it a a guide the " slap" the round into the open ejection port. This is done weak hand, right side up.
For a complete reload I roll the gun and press up on the shells with my pinky or ring finger if they are sitting to low to grab easily. I grab them between my middle and index fingers and use my thumb on the base for support. I pull them out position them nose down on the gate and use my thumb to drive the shell in, once it starts to enter the mag tube I pull my middle finger in and use my index finger as a guide along the top and I rotate my wrist and thumb like a lever to seat the shell past the detent. Repeat till full, rotate and go. This is done strong hand.
Just go slow and practice getting them in there consistently. Don't worry about a proper technique as much as finding a safe and consistent way that works for you. You're going to tear up your thumbnails and cuss a lot but in time you'll be impressively fast.