Don't dive with anyone that makes you uncomfortable.
I do 4 or 5 solo trips a year and have very few problems, but this is a long post because it is a subject near and dear to my heart.
On boats where a group of 6 or so goes with DM they will usually find you a buddy. My recommendation, though, is to scope out the group early, identify the other solo divers and pick out the person you want to buddy with ahead of time.
Use the boat ride to get a feel for your new buddy --- experience, what sort of buddy distance they are comfortable with, etc. Be open and honest with your new buddy as to your experience level, and any concerns or particular worries you have. Go with your gut ---- if while chatting with him you get the feeling he is a flake, then pair with somebody else or the DM.
The more someone brags about how wonderful a diver he is, the more likely he is to be a flakey buddy.
Choosing a buddy, and truly agreeing on a dive plan, is more critical in places where DMs don't go in the water. Don't make assumptions --- go through all of the relevant dive plan details such as pressures for turnpoints/ascent, who leads, overall pace of the dive, what the general navigation route will be, intended depths, what sort of ascent and stops you plan, etc. Hopefully you can also compare air consumption rates, but a lot of divers don't really know their SAC. I do a spg comparison when I hit 1800-2000psi during the dive -- this calibrates me on what my buddy's air consumption rate is vs. mine, and from then on I'll have a pretty good idea how much air he has.
As with all buddies, look each over for location and operation of things such as octo, weight release, BC controls. I tell my buddy about things in my pockets such as shears, slate, and signal tube.
The most challenging problem for a solo traveller is when they get on a boat where all others are already existing buddy pairs. You will end up going with one of those pairs. In the worst case, you will essentially be a solo diver tagging along behind a buddy pair that is oblivious to your presence.
If you are a relatively new diver, one last bit of advice: if the boat pairs you with a diver who moans and complains about being buddied with a newbie, change buddies fast.
Charlie
, when diving I too usually end up solo. My wife is my dive buddy, but she almost always runs out of air before me so I buddy up with (Fred.......camera) and stick not too far from the boat and dive solo. If I run out of film I find subjects and direct other photogs or buddie teams to take a look.
