Titty Magic helps alot when first starting out with breast physics (
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tittymagic.4067/). Regarding fine tuning them, I'd say stick to the "F Breast Physics 2" tab, as the changes made in there are much more managable and noticable on the fly, so you can play with the sliders in there to get a quick grasp on what everything does and how you can work them best with your model.
Take in mind also that there's many custom morphs focussed around breast/nipple morphs that will create a sort of "invisible barrier" as it were, regarding collisions and clothing physics interaction, so if something seems off make sure you play around with any custom breast morphs to see what the culprit is.