Depends which part of the congress you’re talking about, the senate or the House of Representatives.
And as such I’ll do both, starting with the senate. I believe that the senate should serve [at most] three four year terms. Secondly for the House of Representatives I believe that they should serve relatively similar terms, which would be two five year terms. I also believe that there should be elections held every even year for the House of Representatives, for the senate, on any even year 1/3 of the senate will be up for election.