As mentioned before put your kit together before you leave, I like to put a fair bit of air in my bc before I leave, if I capsize the inflated bc will help right the yak also my kit will float not sink if it breaks free.
When I come back from a dive I tether the bc and inflate, dump the weight belt, remove bc then rest the top of the tank against the kayak, with one hand push my tank up from underneath on the back of the kayak, quick kick with fins on while pulling up on the kayak and I am on. At this point I will say 49.8% of my kayak dives are now with the AI, 49.8% are Polynesian style (one outrigger) and the last .4% are off the adventure only , so I do dive of a very stable platform most of the time. Sitting side saddle even with just the Adventure I find it easier to put the bc on sitting on the kayak, specially if there is any form of current.
When I first started diving from the kayak I would anchor and try and put the bc on in the water, I found if the current/tide was running I would keep getting pushed into under the kayak or the current would keep trying to pull me away from the bc that I was trying to fit. If I detached the bc from the tether I could get the bc on but I would be washed away from the kayak and would have a hard slog back.
After a bit of shallow practice I found I could put the bc on easier if I stayed on the yak. Sitting side saddle fins on (these help with stability) first I fit weight belt then I roll my tethered kit into the water and bring it around in front of me. Double check tank on, reg flow etc, bc inflated (this pushes bc open also helps float it) unclip left shoulder strap on bc, holding left shoulder strap in left hand and right hand inside right strap I lift the bc out of the water around my right side and rest the tank base on the kayak gunnel behind me, as it comes around behind me I slide my right arm through the strap (if you have a GPS/FF mounted watch it with the tank), with the left side open I can just roll/wrap the bc into position, clip shoulder strap and fit body straps etc. The fins really help you keep stable during this process, once the bc is on, make sure everything is untangled and working, fit mask reg in gob I hold on to the gunnel and roll forward while turning towards the kayak, holding the kayak helps keep it from rolling over with you.
I always tow the kayak with me when I dive or run a reel off the anchor line when/if I choose to anchor. Generally I will try to position myself that i will drift into the area I wish to dive while gear up, I run my anchor line out without the anchor, it has a short length of chain on the end to help it sink, this will let the kayak drift with me in current but will slow a wind drift if I get separated from the kayak (theory).
All my dives these days are no more than 15 meters and feel comfortable enough to solo dive, its not for everyone and it is something only you can decide on, is the risk worth it? I have dived with some that should have never been given their certificate and feel safer away from them, also dive often with photographers and nine times out of ten you end up separated far enough that I would define it "solo" at least a couple of times per dive even though you plan to dive buddied up and can see each other the whole time.
Anyway thats my bit, just dive within your own limits and have some practice runs with some buddies first at least.