For projects, I always ask for 25% up front and I haven’t had any push back from that.
Once people become more long-term or monthly clients, I do not ask for it to be paid in pieces. Instead, I invoice around the 15th of each month with the total for that entire month. No deposit and they already have the first half of the month’s work completed.
I have found this helps foster the relationship and shows my credibility.
ANd yes, never work for free!