In theory, you should get better at estimating as you do more of this, but that probably isn&#x27;t very helpful right now. Until then you should probably just charge by the hour (or day or week), and if you give the customer an estimate, make it clear that it is an estimate and not a guarantee.<p>Also, you should consider adding a rush fee, partially just to give yourself some buffer. (But also to separate the folks who <i>actually</i> need it fast from the ones who are just jerks.)<p>Oh, and one last note: the customers that pay more tend to be more pleasant to work with. So those &quot;far too high cover-my-ass estimates&quot; might not be such a bad idea sometimes ;)