Hey, Micus, these guys can give you some pretty good advice. I just started boating the MO this summer and learned a bunch from Crazy, Fishinbuddy4 and some of the other guys on the site. I'm getting almost as comfortable on the river as a lake. Longestriver.org has some good pointers and advice, as well as good explanation of channel markers, etc.
Probably the biggest thing I learned was to keep the motor running until you're sure the anchor has caught and bring plenty of gas
I'm not nearly an expert, but the one thing I do know is that the only way to get comfortable with it is to ask questions and go out when you get the chance. This site saved me from learning a lot of things the hard way. Good luck and enjoy it!