I too had this problem earlier in the year. Around Feb/March I was really stressing out with regards to 'am I good enough?', 'is the story finalised?' etc etc. Eventually, after a lot of anxiety and being objective with my work, I decided to take the plunge and launched in August this year.
I definitely recommend 'just doing it' because as above posters have said, your art will improve tremendously as you address areas to improve on week-on-week. Being realistic about the update schedule helps massively in this regard as it'll help you fit in study time when you get a free moment. Just don't push yourself too hard, especially if you've got a job/household stuff to be getting on with.
I personally keep an evernote document with what I have to do that day, a post it note on my desk with my comic workflow (it can take ages as it's all traditional so I experimented with the order of steps e.g. lettering, inking, ruling lines until I found one which worked for me). But if I can't get everything done I don't sweat it and concentrate on the high-priority stuff as much as possible.
A huge part of this is also decluttering. These past few months have had so many things to get ready. I host my comic elsewhere as well and have to do cast pages, extra art, backgrounds etc, as well as getting the thing out every week. So removing the fluff from my to-do list or even moving it somewhere temporarily also clears my headspace. So definitely get organised and get rid of mental/external clutter before starting anything comics-wise for the day.
As for the act of doing it - I usually put on music, or youtube videos with interesting topics. As I know these are a predetermined length, it makes me work to see how much I can do within that time. It becomes kinda like a game. When I'm racing towards the deadline I listen to extended music tracks as I know I'll be buckling down - when the track's over I know I've been working for 30 solid minutes. And then I take a break - maybe call my parents, check the forums, respond to texts etc.
Recently, I've just been looking after myself a bit more with regards to eating better/sleeping at reasonable times (and not getting mad at myself if I can't!) and making sure I'm not being too hard on myself. It's a process and I didn't get to this 'reasonably fast and balanced lifestyle' point overnight. But I'm able to work on the comic a lot easier now. So just take it day-by-day and keep on learning as much as you can.
This ended up being a long post, but if you want to know specifics just shoot me a PM. Good luck!