really warms my heart to see how many ppl have reblogged this with tags or comments about how having a fursona has improved their life in some way, or (even cooler!) how this post gave them enough of a push to start thinking about creating one! i kinda just wrote this post on a random whim and didn't expect such a widely positive response.
for me personally, my sona often fluctuates between being a very personal and euphoric self-insert that i can project ideas and emotions onto, and just sort of a funny little art mascot i can use to represent myself online, so sometimes i kinda forget just how dearly beloved these little personalized critters are by a lot of people. like "making a fursona and having that as an emotional outlet saved my life" type stories. it's cool as hell and i'm really happy for them!
however, a lot of folks who are in the "i don't have a fursona but now i might wanna make one" camp seem to frequently be unsure where to start with this stuff, though, so i thought i'd offer a little advice for that!
first thing is that this process is gonna come down to a little trial and error most of the time. none of your decisions are set in stone, you can always change things up later as you see fit (and hell, you can even have multiple fursonas for varying moods/purposes/etc if you want! people do it all the time. also, lots of folks give their fursonas hybrid traits, like a cat-dragon or a shark-wolf or a griffin or whatever, so that's an option too! mix-n-match)! people are complicated and a fursona always serves as a great canvas for personal experimentation and expression, whether you've had them for a decade or a day already.
focusing specifically on the choice of animal tho, it's handy if you already have a favourite animal for one reason or another (maybe aesthetically, behaviorally, symbolically, or some mix of these) but your favourite animal isn't always gonna be one that you think really represents you personally. that's fine! i adore cats IRL but i could never really see myself having a cat fursona. the important thing is that now you're THINKING about making a fursona, so now you can keep your eyes and ears open to inspiration when it comes along. i originally just picked a bunny because they're cute and cartoon bunnies are pretty easy/fun to draw, but as time went on i picked up loose knowledge about their traits and behaviors and realized "hey, i'm quiet and polite and loud noises make me anxious, i'm happiest sleeping and waking up at unusual hours, i like to feel small and cozy and safe, i'm a little bit mischievous but bad at serious confrontation... maybe this was a better fit than i thought!" and now i can't really imagine myself picking anything else. got it in one. but if i HADN'T lucked into that on the first try, those kinds of observations would've helped me get there eventually. look at animals, learn things about animals, and keep the thought in the back of your mind of "do i feel a connection to any of this?" as you do so. something might just click into place one day!
failing all that, idk, just pick a critter you think looks neat, give it a couple colours and some cool hair or whatever, and see what happens from there! not everyone's fursona has personal meaning to them and that's fine too! also, if you have a friend who knows you decently well (especially if they're an artist) you can usually ask them for creative input and bounce ideas off them. friends are often really good at putting a finger on unique defining qualities that you may not have noticed about yourself, and that can help a LOT with this stuff.
anyways that's all the advice i got, hope it helps! even if you don't end up actually settling on a fursona, or feeling like this is right for you in general, you might still benefit in some way from the process of reaching that conclusion and i sincerely encourage you to give it some thought if it sounds interesting to you. have fun out there!