Advice for Tying Someone Up?

[justinlogget]

For context, I had a meet up a few weeks ago and I tried out tying my friend up. I have some experience with rope and I did everything with wrapping the rope around his wrists and cinching it in the middle. I tried to connect it to a chest harness but he ended up being able to slip his wrists out and slip out of the chest harness. Any advice on how to stop this? I tried it 2 more times and he slipped out each time, even when I tied his hands a different way.