I agree with Louie... In fact, IMHO, diving holidays are more fun as a lone traveller than a regular vacation, because you are joining groups of like-minded people and can easily socialize during and after diving. I've been to several resorts in Asia with friends and went solo last Feb to charming Scuba Club in Cozumel. Going to Roatan (Fantasy Island resort) next week solo!
When going solo I'd recommend staying at a dive resort vs sign up at a dive shop, because it creates the intimacy of summer camp: you will be diving, eating and relaxing with the same folks everyday. Depending on my mood I just asked if I could join a table, or, if I wanted to read, then I sat at my own table.
Dive resorts usually assign you to the same boat all week. As for buddies, I usually talk to the DM so they can assign me a decent dive buddy who is appropriate for me (If I am nervous I ask to dive with the DM.) I'll try to find someone who breathes the same amount of time as me to max my BT, and/or likes to look at the same stuff.
The resort people all know you are alone but they're usually really nice to me. I will make an effort to remember all their names, chat etc, but won't flirt too much --- sometimes men in other countries have misconceptions about "loose" American women based on what they see on TV.
So, go explore and have fun! :mean: