I think the best answer to this problem is for the diver to develop a specific order of donning the gear, a check list if you will. For me, I always follow this procedure once I have setup my gear on the bench:
1. Check all valves are in the correct "open" position
2. Smell the air from each regulator
3. Breath each regulator, clip primary to RHS shoulder D ring
4. Test inflation/venting on wing/BC
5. Arms in harness, shoulder straps positioned correctly and not twisted
6. Backup regulator around neck
7. Dry suit inflation hose connected
8. Test dry suit inflation
9. Waist/crotch strap buckled
10. Unclip primary, route long hose, reclip primary
11. Check backup lights correctly stowed and off
12. Turn on, check, turn off primary light
13. Enter water
14. buddy gear check. Your buddy/team mates should understand your gear configuration in order to properly perform a pre-dive mutual gear check. This is important if you are not diving the same configuration or if your buddy is not a "long hose diver".
15. While standing in the water, test your deployment of the long hose, this will ensure the host is routed correctly and that there is nothing over the top of it (harness, light cable, etc). I also test deployment of my cutting tools and check the contents of my pockets (e.g. lift bag and spool, wet notes, double enders, etc)