Ive just been learning pop up attacks which i have tried to explain below. Im no expert but happy to share what I have learned. It has totally changed the way I play dcs which now feels like a brand new game. If ive made some mistakes feel free to correct me.
To learn pop up attacks all you need is training rounds, smoke rockets and nothing else (ditch your tgp). Find a field and fire smoke into the middle of it. Slew your hud onto the smoke (this is your target) and tms up long it. Set your tad so the outer ring is at 5miles. Get about 7ish miles from the target and fly as fast as you can as low as you can (under 100ft). Fly offset to the target. When the wedding cake on your tad is at the 3 o'clock position just outside the inner ring (just over 2.5 miles out) pull up and look for the target it should be just infront of your wingtip, roll onto your side (keep looking at the target it will now be above your head in the middle of the canopy). Pull back on the stick, the target will travel down the canopy, roll over a bit more when the target is coming into your hud so your nose is pointing down (you never want to he pushing up with the stick). Line up your target, you should still be about 2.5 miles away (hopefully just out of range). Shoot that bas@#rd, turn away hard, dump a few flares, jink and get back down to <100ft asap. Keep practicing until you can do it in your sleep and you are comfortable flying low.
This is how the a10 was designed to be flown (so ive been told).