I’m going to assume you’re talking about USFIV…
Well, first you have to ask yourself how you are getting caught by x-ups so often. If it’s people doing a blockstring then jumping, just jump back with fierce punch, or dash forward under them. You can also auto-correct DP, or hit them with a jab either to reset them or as they land for a full combo if you walk slightly forward to make their x-up whiff. cr.lk might go under certain x-ups as well.
If it’s on wake-up, most loose x-ups can be auto-correct DP’d. Or use DWU.
As for the follow-up, remember that unless the jump-in attack hits deep or has lots of blockstun (eg. off a hard attack) there’s usually a gap for you to do something before their next attack. Mashing backdash will get you out of most mixups. Mashing EX DP will beat their follow ups, but they could also do delayed throw after blocking. If the jump-in hits really deep, they can’t throw you immediately and you should be able to react to walk-up throw. However, they can also do cr.lk as you react to the throw. This is a mixup. Mashing backdash will evade both options. Mashing EX DP beats both options. Off deep jump-ins the follow-up is almost always a true blockstring unless it’s a throw or the opponent is intentionally delaying their attack. You cannot backdash or reversal out of the follow-ups if they don’t delay them.
At the end of the day, the safest option is really to just block and tech, and mash backdash between gaps.
It’s worth setting up the Training Dummy to perform some x-up strategies that you have trouble defending against and then trying out different things.