OUGHHH its kinda hard to explain bc i just . kind of do and decide what looks good or not … but i have massive pinterest boards full of traditional clothing which direct how patterns should go 🤔 normally if the pattern and detail is rlly complex i just duplicate it over and over to get basically a sheet that i can put on a clipping mask and i adjust it using transform and liquify until im happy with it! i also have a couple seamless pattern brushes i downloaded for free just to add texture or to fill out the flat colour a bit more if that makes sense 🤔