I'll put the full thank you post up at the end of this story, but I want to write a bit on why I'm encouraging you to show your thanks by writing to the artists. Find their art site portfolios! Bookmark their comics! Follow them on social media! It does matter, because, as internet-based artists, a lot of us work in a vacuum. (This means social media is especially vital for reaching people. Give following a try, even if you don't like reading about me playing Animal Crossing.)
When we see words from others, it makes an impact. Art is low-paying and high in work. (It can easily take a decade or more of practice just to bring some simple doodles to your screen.) It's very stressful, and one of the best ways to keep motivation is to feel the positivity coming from readers. We're all at different stages of development, with different motivations and often one-person operations - so someone going out of their way to send an encouraging note can help keep a veteran going or inspire a novice to keep grinding when times are hard.
Whether it's this crew, or some other artist you admire - Go send them a quick note saying you like them! Sure, it can make everyone nervous (artists rarely know how to handle compliments, even if they need them) but it's so important. For every kind person who hesitates, someone with less self-awareness doesn't have that issue - and that makes feedback perception somewhat skewed. Balance that out by being respectful! (Also, assume that creative people know what they are doing!. Yes, it's odd that I have to mention that, but I do.)
Financial support - buying book/merch, supporting a Patreon, sending a donation, etc - is, of course, very vital. Comics may be shown to you for free, but if the finances aren't there, those free comics will stop appearing. Financial support also can't always happen, so typing out a few nice sentences can still be helpful.
In my case, kindness is everything. My medical bills total more than my yearly income, and because of my condition I can lose entire weeks of work time. Having these guest artists all go above and beyond is so amazing and inspiring. These people stepped in to support me when I was hurt, and watching readers love what was created makes my fight worthwhile. Positivity keeps me pushing. Writing to complain I'm not making as many bonus comics as before brings me down fast. (No one's done that. I just made up an example.)
Another interesting note is that, like most forms of entertainment, the top 1% gets 90% of the feedback. (I'm barely a blip on the comics scene, so almost all of my feedback is from the comments.) If you want to praise a big name, definitely do so - but do understand if it takes a long time for a reply, or if the reply is short. This can also apply to less-known cartoonists, because effort doesn't scale with readership. We're all hardworking, but lesser-known artist might be able to give you longer replies and advice due to low volume of emails to reply to. Showing kindess isn't bothering an artist. Well, unless you tell the artist they are better than another artist. A lot of cartoonists are friends, so that doesn't make us happy. Stick to only nice things. Long notes are nice. Small notes are nice. Heck, don't underestimate the value of an email that merely says something along the lines of, "There's no need to reply to me. I just wanted to quickly tell you how much I appreciate what you do. Thank you."
Make it a habit to be more vocal in encouraging creators you like - especially lesser known ones who don't always get that attention. It's intimidating sure, but it can do wonders for everyone involved. Go and share the good vibes - but don't write to me! I'm not fishing for emails (this time), and I'm too sick/busy to give you good replies right now anyway. (It's not that I don't love those emails, but I want you to go spread happiness to lots of creators!)