Thanks for the write up @Sabii !
I would add: If you are on IDR, you can still make extra payments - it won't change anything. So if you have a bump in pay or can afford more but don't want to commit to paying more every month (which makes your finances more flexible), you can totally do it.
For example: I have my regular payment set up through the system (for the .25% reduction), but have an additional amount recurring using my bank's bill pay. If I have a windfall, I might send a one time payment as well. In the end, I can turn off the billpay from the bank without any issues or changes to my regular payment.
Offset income by investing more into a 401k/IRA/FSA plan. The lower your AGI, the less you pay and more you have invested into retirement. This usually only works well if you owe a lot of money on loans and plan on utilizing some type of forgiveness.
^ +1 You can also use that trick to continue/maximize getting your student loan interest deduction if you're over the income cut off.
2019 phase out starts at 70k and ends at 85k