Much of the community surrounding MMD appears to be non English speaking. So it's been a bit difficult for me to find models and quality tutorials. I did find a guide for converting SFM models to MMD format here: https://learnmmd.com/http:/learnmmd.com/convert-sfm-gmod-models-into-mmd-flawlessly/

Seems useful as SFM models are abundant and easy to find, though I've yet to try this process. Honestly, I'm trying to use PMXEditor as little as possible as it seems extremely cumbersome and halfway translated.

If anyone has resources they can share, please do!