In my total webcomic career I've made about $7 dollars from ads, that I never even got to see, but that's ok, I know I'll make money in the future. For now though I'm in the same boat as the majority of you. However for those who are ready for the massive investment and headache that it will be to make a living from your cartooning I recommend you check this out: http://www.djcoffman.com/cash4cartoonists/
Its a small e-book, but it contains a lot of good information on where to start bringing in the cash. :D I think the money aspect of my art is very important. Making money from your art builds a lot of confidence in your abilities and your self esteem as an artist, but its not for everybody.
I think this common problem is why it is important to write down my storylines and flesh them out completely before I even think of putting a line down on the paper. ( Or at least in Hipsterish's case write 2 or 3 chapters ahead of time ) This allows me to make a guesstimate on weather or not I'll still have enough steam in me to continue the project and also allows me to scrap dumb ideas earlier with out all the stress of feeling obligated to follow though since I've come so far.
The longest I've had a project in "cold storage" is 7 years. Its still awesome, I still love the characters and though the setting has changed a couple of times I still feel excited about when I'm able to finally commit the project to paper.
Depends on what kind of comic I'm working on. Hipsterish for instance is just drawn with all of the ideas in my head, very spontaneous. However my graphic novel projects art written out as general outlines of the story's beginning, middle and end and then more detailed scripts of whats going to happen on each page.