First off, write high quality code. High quality code requires less maintenance. Keep everything separated out properly so that clients can do some updates them

First off, write high quality code. High quality code requires less maintenance. Keep everything separated out properly so that clients can do some updates themselves (e.g. update the text here or change that color to this color) and make sure to stipulate in the contract that you are not responsible for such changes. Write comprehensive test cases. Possibly, limit the contract based on these tests.