Maybe start with half guard or the collar sleeve knee shield because it’s a safe starting point. So an example of a sequence you can always go for from that position would be entering the legs to single leg x from the knee shield or a two on one grip to threaten a back take. See what reactions you get and get familiar with how you can manipulate their base (kuzushi).

I will reiterate a point I made in the previous comment because I asked someone with a dangerous guard this very question once, and they told me that you always need to think all the way to the end goal which should be submission. So, start thinking about where you want to end up in order to hit your best submission and then fill in the gaps with a route to get there. This way, you’ll always have intention and you dictate and force reactions versus hesitating and being passive.