I have been generally just looking through year end lists of the best new music for the year and spending the next few months going through that, but I feel there may be a better way.
I'm often too lazy to really search for new music so Spotify radio is perfect for me. I just search for a band I like and listen to "their" radio. Songs of similar artists are added there and I already found some really great bands while listening.
Mostly through RYM. You can always easily look at what the best rated music of the year so far is (it's the default chart) and it's always interesting to see how high brand new obscure releases chart (though most of the time they eventually drop at least somewhat)
All over the place personally. Usually I use spotify and reddit, but in a post-reddit world that isn't an option, so hoping this community can fill the void. I also get songs from online radio stations, which I have a full bookmarked folder full of. If you want some names: laut.fm, tunein, somafm, streema, radio.net, and onlineradiobox all have legit stuff. Also word of mouth is often pretty good too.
Some smaller artists keep personal playlists on Spotify, so that's a good source. Also, I like the playlist search tool I've linked below - search for a song and see which playlists it appears on. You have to filter out Spotify official playlists otherwise that's all you see.
https://www.chosic.com/spotify-playlist-search-tool-by-song-or-artist/
I'm an old school guy, so I'm still following a lot of blogs (shoutout to Brooklyn Vegan, The Line Of Best Fit, Gorilla vs bear and Clash in particular) but if you use Spotify, EveryNoise is amazing. You can either look up genres or just browse their MASSIVE new releases page, where you can filter all the genres you're interested in and make yourself a nice custom one. https://everynoise.com/new_releases_by_genre.cgi This website was a real gamechanger for me. I spent like an hour there every week, just listening to the previews. Honestly the biggest reason why I still didn't leave sinking Swedish ship, I don't think there's a good equivalent for different platforms.
Also hello Lemmy (my first post here, posting on r/indieheads regularly, here mostly just in case anything happens)
This is going to sound really weird but...Eurovision. Obviously it's not all (or even majority) "indie" but there's always a fair bit and I enjoy being exposed to music from other cultures.
For example this year's major find are a Finnish band called Kuumaa, who Google insist on classifying as "pop" but never mind. Particularly their song from the Finnish national selection this year "Ylivoimainen". Shoutout to Sudden Lights from Latvia and Joker Out from Slovenia this year too.
Spotify is the most common way for me with their "For You" and radios. Other than that, it's openers at concerts, AltNation, and a Facebook group I'm in.