Can i reduce the likelihood of trapping bacteria under sealants? how do i do this?

Is not a problem: The whole idea behind dental sealants is to prevent bacteria from getting into the grooves of the teeth. If you have a sealant and it is intact no bacteria will get under it. If you are going to have a sealant placed the dentist/hygienist will clean the tooth first before placing the sealant. As always the best way to keep bacteria off your teeth is slow, gentle tooth brushing twice a day.

No: You can't. The dentist will clean the tooth before the sealant is placed, but after it is placed, there should be nothing getting under the sealant unless there is a problem with the sealant itself.