2airishuman
Contributor
What I've found from searching is most people (that don't put it in a thigh pocket or clip it to their waist belt) use either bungee loops or a Dive Rite sleeve and then attach it to the side (opening facing down) or bottom of their back plate. Some people clip it to the butt D-ring on their crotch strap.
I carry an SMB on most dives as a safety measure. I used to have a nice SMB with an integral sleeve, and I put some pieces of inner tube around it so it would stay secure, and attached it to the butt d-ring with a bolt snap. It came off and was lost on a recent dive. Unfortunately, I was unable to recover it.
I had previously used the XS scuba mesh sleeve attached to the side of my back plate and was unhappy with the streamlining. Now (having purchased another SMB) I'm experimenting with using the XS scuba mesh sleeve on the bottom of my backplate, which seems to work better. It fits between the cylinder(s) and my buttocks and although I can tell it's there it doesn't get in the way. Access isn't the greatest but I think it will stay put.
If I re-stow it during the dive without help, I would wrap line around it from a spool and clip it off somewhere else, probably a waist d-ring, for the duration of the dive. There's nothing that says it has to go back in the same place. If I really wanted it back in the sleeve, I'd have to take my rig part way off.