My favourite policy suggestion for that: make it so that student loans can be discharged in a bankruptcy like any other loan. (Or more precisely, new student loans taken on after the new policy takes effect. No retro-active loan forgiveness.)
It's my favourite policy suggestion, because it's a common populist complaint that student loans stay with you forever. So my suggestion looks like it's giving in to that populist sentiment.
What is actually does: most students have no assets just after graduation, so bankruptcy is 'free' for them. Thus lenders can't count on getting the loans repaid, and thus won't loan as freely. Cutting off the spigot of student loan money will bring down the price of education.