i'm a bit late to respond, but sure thing! i haven't played in a really long time, but i think i can help you out.
overall you want to keep the opponent at the tip range of your sword unless you are severely behind in damage. spacing for sieg is a happy balance that requires a lot of practice to figure out, so don't be discouraged if it takes you some time to master it.
don't attack after 2A, it's fairly negative even on hit. you can potentially try moving after it though, depending on what your opponent does, but it's still dangerous. that's not to say don't use 2A though, its a not-terribly-slow low horizontal poke with ok range (though sometimes characters can step through it).
don't use A+B or A+BA. they're pretty bad moves. I also wouldn't use 66A unless you're expecting a horizontal GI; the move is very very punishable on whiff, and duckable on reaction. and the GI is pretty situational too; if you really wanted a horizontal GUI, you're probably better off with SBH GI unless you need the GI from crouch.
You also might do better using a faster move like b6 to interrupt your opponent. And poking your opponent with fast moves like 3K, 1K, and 66K can also do wonders for you
66B force block on wakeup is generally good, it stops rolling, but you might do just a little bit better by trying to hit more with the tip of the move so that it's harder to punish. that's a good generalization for siegfried; things are usually harder to punish if they are done at tip range. there are some characters however who can punish you regardless of range.
you should learn how to do the move "agA". it's siegfried's best horizontal, it's + on block, and it's one of the best horizontals in the game. it also does decent damage, is required for some combos, it rings out, and it kills step.
you might want to sidestep a little bit more. those xiba BBs were tearing you up pretty good in the beginning there. also it might be good to learn the difference between step and 8wayrun. step tends to be better for evasive maneuvers (just tap 2 or 8 instead of holding them down and you will step. hold them down and you will 8wayrun. double tap them and you will quick-step).
3B is so punishable you may as well enter the stance transition every time. if you want to block, you can always cancel out of the stance transition with G afterwards, but because 3Bs stance transition is decent on block, you can potentially interrupt your opponent with SCH K, depending on what they do. this tactic isn't fool proof however, and can be beaten; some characters can beat the SCH K outright, and everyone can sidestep it and potentially punish you with a sidestepping TC, with the best case scenario forcing you to re-align, so use it with care.
if you don't know frame data, you would also benefit from checking out the frame data thread or the wiki:
https://8wayrun.com/threads/siegfried-frame-data.8848/
https://8wayrun.com/wiki/siegfried-frame-data-sc5/
if you'd like to learn more in the way of combos, we have a thread for that too:
https://8wayrun.com/threads/siegfried-combo-tech-trap-list.8847/
and we also have a punishment list for siegfried available if you're looking for more technical ways to retaliate against your opponents. punishment is very important at higher levels:
https://8wayrun.com/threads/siegfried-punishment-list.14266/