You want to make sure if you do have gravel, it is a smooth gravel (no rough edges). Generally most generic aquarium gravels are smooth, but I would double check just in case. When rinsing new gravel, I always stick my hand in the pile to make sure there are no sharp/rough rocks in there.
Gravel can be a bit of a pain however, as I find I'm gravel vacuuming at LEAST once a week, sometimes twice to get all the stuff out of the gravel. My corydoras get sinking wafers at the end of the day (giving them the rest of the day to clean up any left overs from the tetras). As the sinking wafer softens, it falls in between the gravel where the corys cannot reach it. Then I end up having to gravel vacuum it up.
I'm looking into switching to sand for the sake of easier clean up - the corys love rooting around in sand and can reach all the crumbs of food. I'm told you just need to rake the sand about once a week to make sure it gets rotated so that no bacteria builds up on the bottom.