I forgot to mention these examples I also just hear “shhtoh”. After reading through all the advice, I’m going to keep listening to examples until I can start to hear the accent, I doubt I’ll be able to reproduce the sound until I learn how to hear it.
It’s fine to do it the other way around. You may still hear shhto but still be able to map that to the way your mouth makes the sound and get the proper association anyway.
Try both methods and see.
One thing I’ve noticed while I’ve been practicing: in Japanese, your two rows of teeth are always much closer together than in English. Especially with い-sounds, where native speakers look like they’re biting on a sheet of paper. I’ve even read that a good way to practice phonology is to bite down on a pencil while reciting the kana.
In addition to what @alo said, try consciously to keep your teeth extremely close together like that when you make the ひ sound. You’ll feel how it can sound like し as the air passes through your teeth.
This is a really weird way to understand it, but I think of it as half of the breathing exercises pregnant women practice for giving birth. There’s three “he he he” breaths that have the same sound that I’ve heard in the pronunciation.
Ultimately, you’re shaping your mouth like you’re putting your vocal chords into saying “ひ,” but you’re blowing the air out instead. This also means that your tongue is not as out of the way as it is if you’re vocalizing ひ。It’ll be closer to the roof of your mouth, but not by much.
These are probably not the best explanations, but the second one was what I was introduced to, and the first one was what really helped it stick for me.