Ugh that's such a classic problem. What finally worked for me was being super direct and saying, "Hey man, I have to keep that stuff as paid work to make a living, but I can swing by Saturday morning for a quick look." It sets a clear line but still helps a friend. If he pushes back, you'll know he just wants free labor.

Schedule your admin work like it's a client meeting. I block out two hours every Monday morning for emails and invoicing, so it never spills over. For receipts, I use a phone app that scans them right away, no more digging through piles. Set up email templates for common replies to cut down on typing time. And always, always put client calls in your calendar with alerts, so you don't miss them. It sounds basic, but batching this stuff saved my sanity.