So the first thing that usually happens is this: You get hooked on an anime series or video game. Then because you have a slight talent for art draw some short comics and decide to post them online. Voila! You're a webcomic artist. And now you're addicted. People like what you drew and you decide it's time to become serious and not just make random comics but make it a series.
In the beginning you make lots of mistakes and usually after awhile you get bored with your idea and abandon it. Such is the fate of many a beginner. I think it's how nearly everyone gets started.
It's certainly how I got into it. Although for me, I was unaware of this concept called web comics. I just liked posting my pictures online and some of them were short fan-comics. This was back at the new millennium when telnet MUDs were the MMOs and geocities the only real place to upload a free website. Around this same time I discovered my first few web-comics by veterans NeonDragon and Luka Delany. Inspired I tried it for myself with something original.
MSK was intended to be an online graphic novel like NeonDragon's comic Timescapes and she listed hosting. For awhile, I just posted on geocities before transfering to drowtales. Drowtales recently dropped the comic hosting and MSK now resides at Comic Dish (mirrored on Drunk Duck).
Before jumping into webcomics there were very few things I considered. Like how much time I would dedicate to it and how much school would interfere. Some things I wish I knew before I started, like better site design and how long it would take. I assumed that MSK would be finished by the time I graduated high school or at least a little bit into college. It ended up finishing about the time I graduated with my undergrad degree instead.
But I did do a few smart things like, prepare buffer, I could draw fast, and I met a lot of great people.
For me I recommend coming in easier before trying the graphic novel approach. It takes much longer. Now there are many many more resources for first time web comic artists/writers that I did not have at the time.