Due to very young family and work commitments I have to paddle very early or very late and normally at short notice so 99% of my paddling is done solo.
I judge the conditions carefully and stay well within my limits. If I have any concern I stick very close to shore so if it all goes wrong I am close enough to swim to shore almost instantly.
I carry all the kit I need to self rescue (paddle float, coaming stirrup etc) as well as kit to make contact with the outside world (VHF, Phone etc).
All that said, paddling solo has the extra risk and no matter what precautions we take we could get into serious bother. However, I have to weigh up the enjoyment I get from paddling with the risk and I wouldn't be the person I am if I didn't paddle. I have the support of my wife/family and they trust me to make sensible decisions.
At the end of the day, if I'm concerned I walk away - the ocean will be there tomorrow and I want to be there to enjoy it!