Hi Joe, welcome to IDO! Navigation on the Mississippi is the same as all other inland waters. If you are headed up stream, keep the red bouys on your starboard side and the green to port. If you are unfamilliar to river navigation, now is a good time to learn as levels are low and slow. Keep a good watch for unmarked hazards. If you are coming into St Paul, there is a ramp at Lillydale regional park and at Hidden Falls park. Also there is a ramp in south st paul that is fairly close to the free way. All of these are an easy launch this time of year.
Fish current seams and the faces of wing dams. Slack water usually holds fish and most fish are on the bottom of the river, thus the poplularity of 3 way rigging, vertical jigging and lead core trolling. Find the bottom and you will find fish. There are people on this site that fish p2 almost exclusively and are a better resource than I am. The key to learning a new body of water is putting in your time. If all else fails, you can hire one of the many guides that frequents this site. This will take years off the learning curve. Have fun and keep your PFD on with the cooling water temps. GOOD LUCK!