Don't take tiny bits of work that are due in two days. But if it's a bigger piece of software, you can tell them "It'll be ready in 6 weeks" then you'll have ti

Don't take tiny bits of work that are due in two days. But if it's a bigger piece of software, you can tell them "It'll be ready in 6 weeks" then you'll have time to do it on your own schedule, assuming you really don't need 6 weeks fulltime to do it. And set up a time limit, and a high rate, for maintenance and bug fixes, so they don't keep calling you six months later to add this or change that.