The House and the Senate need to reconcile differences found in their version of the different tax bills by going to conference. They can also decide to forego that process and simply vote on the Senate version instead.
Right now, the best strategy is to contact these House members who have gone on record as opposing the tax bill, opposed the healthcare bill (the sections that repeals parts of the Affordable Care Act), or who come from high state tax states and have expressed concerns about terminating the State and Local Tax (SALT) deduction.
While specific attention is being paid to Reps in a handful of states, everyone should keep up the pressure. You can find your Representative’s number, email address, Facebook page, or Twitter account information online by using your zip code at Contacting Congress.