Biden has already addressed many of them. I will leave you to do the research to find out what he has done along those lines.
Reduce the Deficit
Do something (anything) to try to slow climate change
Put effort into relationships with our allies.
Bring production of technology back home from overseas (specifically China).
Pull our soldiers out of wars in the Middle East.
As far as his popularity goes, there are other factors. A good portion of the country wasn't going to give Biden a chance regardless of what he did (just like The Former Guy). Also, the economy rules, and it is easy to make POTUS the bad guy when the economy is facing hurdles. Add to that the fact that he is extremely old, and it is easy to see why his approval rating is fairly low. It will be interesting to see how he fares when the economy rebounds.