It's more fun to approach the game with your own personal challenge. I know a lot of people try a new style or technique during this month, like my friend trying single-layer digital paintings. My personal approach this year is thematic. I'm drawing cute couples! I don't usually draw boys, so it's a good compromise if his girlfriend will be in the frame, too. Also, more characters per attack = more points!
These are the characters I drew.
These are my characters, drawn by other people.
It's one of the more fun art communities these days. A lot of communities have turned completely business-minded or are littered with off-topic content. Artfight, however, is necessarily interactive and collaborative, more like how art communities felt in the 10s. I try to play every year to motivate myself to draw more, especially things outside my comfort zone of cute girls.
This community has a lot of overlap with Toyhouse and Tumblr, though, so don't be surprised if you keep running into massive text walls of character permissions and "original character donut steal" warnings. There's also a wide range of ability. I see everything from grainy photos of lined paper to Tearzah copycat artists to university illustration students. It feels like old DeviantART in that respect.
You should know that the servers reliably crash during the first week of July every year, so if you do want to play, prepare during June. Upload a few characters and their reference pictures, find targets you'd like to draw, and save their usernames and reference pictures. Even if the servers crash, you've got everything you need for a few days.