When to send a change order
Any time the ask wasn't in what the client approved. New page, extra revision round, "can it also do X". Small doesn't mean free. If you'd bill a stranger for it, write it up.
How to send it without it being weird
Keep it short and boring. Here's the change, here's the price, here's the new date, reply yes and I'll start. Most clients are fine with it. The ones who aren't were going to be a problem anyway.
Curious what the freebies already cost you? Try the scope creep calculator. Want the whole flow handled? See how change orders work in Scopease.
Lock your next scope free