Good general practice tip is to practice everything on single notes. So practice one double stop until you can really do it well. Or practice dynamics on a single now. For example, play Ace notes as quietly as possible with a millimeter, phone, like a whisper. And then gradually get louder, using the full bowl until it’s ridiculously loud. Go back-and-forth a few times like that. Then you can do the same sort of practice on slightly bigger chunks, 2 to 6 notes.