Hi Tor! Welcome to our (quite small) family of posters here. Out of curiosity, can you tell us what has been your primary source of information about sea kayaking. Books? Internet? If Internet, posts and blogs? Videos? Do you have previous boating experience, especially on open water? You seem to have a healthy attitude about keeping things safe on the water, and it would be informative to know where that comes from.
I paddle / practice solo 90 % of the time. My practice sessions are planned very carefully in advance. (What to practice or what needs work, based on previous GoPro videos from front and rear deck)I look at the videos when I get back home, and determine what is to be worked on during the next session.
I am currently working on getting a solid roll from both sides established. I just feel that without it, I can't push myself or the boat as far as I could with a solid roll. Don't get me wrong, I don't mind capsizing, but it gets old crawling back into the boat when you are practicing something that might end in a roll (edging limits, brace practice etc). So I used a float then graduated to "paddle only" when rolling. Now I am just trying to roll cleanly from all kinds of positions (you just don't have the luxury of "setting up" if you go over unexpectedly.)
Gordon Brown and Ken Whiting are the two main sources I use (DVDs). I don't have any previous sea kayak experience, but being a native Norwegian, the healthy attitude comes from years of boating in the Norwegian North Sea and southern coast of Norway.