Stuff it and puff it. You've gotten lots of good advice here. When breaking them in, I take a few puffs after getting the taste of charring shank, then let it go out. You can make pipe mud to fill in the gaps around the shank insert and bowl, as pipesticks does, but that will take care of itself over time as you smoke the pipe. Leftover bits of dottle and ash gradually build up and even out the bottom of the bowl.
Wipe the inside of the bowl out with a wadded up paper towel after smoking. In addition to getting moisture out of the pipe, it prevents any real cake build up, which is generally undesirable in a cob. I didn't do that for the first couple of years, and ended up having to ream my first cob. I thought a T-handle reamer might mean the end of the cob, but it was fine.
I use the paper filters even though I thought I wouldn't care for them when I bought my first cobs. I also have a few Forever stems, but I've never actually used them. I guess I'm pretty content with the 'stock' cob experience.
Anyways, I have at least 30 of them, and probably 75% of my smoking is from MM corn cobs. I hope you enjoy yours as well.
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