Like some others have said, I don't think "getting interest" is really worth it unless you already have an audience to hype up. Like, there's a billion comics on the internet, with more getting added every day, and some of them are terrible, and many of them disappear after ten pages. If all you have is a promise that you're going to start a comic soon and boy it's gonna be great!! then that's not all that exciting.
If I start reading a new webcomic, and it only has a few pages and feels like the story hasn't really started yet, then 9 times out of 10 I'll be like "well, this has promise" and I'll wander off with the thought that maybe I'll check back when it has more pages, and usually just forget to come back.
When I started my comic (which wasn't on tapas, so that's admittedly a big difference), I got a buffer of five pages, which is the point where weird things start happening in the story, and then posted those at the once-a-week rate that I was planning -- but I didn't start publicising the comic outside of my website until those five pages were up. So, my friends, and folks who'd followed me over from my previous webcomic, got to be excited by the first few pages, but when I started sharing the link around, a decent chunk of story was already up.
There's not really an established protocol across all comics -- you can always ask! Some folks do link exchanges, some don't, some only link exchange with certain comics, etc. I don't do them on principle, so I have a note in my FAQ about that, but if someone like, asks me at a con or something if I want to do a link exchange, I'm never offended by the question! as long as they're respectful and cool about it when I say that I'm not interested. ;u;