Any suggestions on how to start learning fiddle?
I suggest not doing on your own like I did. If you already play instruments then you're already familiar with the time & effort it takes to progress....well fiddle is worse - just more techniques you need to get used to before you can pull any kind of tone out of the thing. I still have days where I pick mine up, play a bit, and it just sounds like crap so I put it back down for a while.
There are many instructional websites and people who teach on the net. I've been doing lessons & workshops through Zoom lately, but have spent quite a few years now hanging out on a couple websites built by instructors...those are nice because you can totally set your own pace.
I use all the tools I can to learn: slowing down video & audio, tablature, notation, personal instruction.
It can depend a lot on what you want to play too. I like to do a searches like "learn Bill's Droopy Britches fiddle" or some such and see what pops up.
YouTube is a great resource. you can see and hear someone play something and slow it down.
I also use software that slows down recordings & can pull the audio out of a video so I can just listen.
Tons of choices out there....but it still takes heaps of time, patience, and perseverance.