Welcome!
If I were new, and just starting to build a stash, first I would think about what kinds of quilts I find most appealing: scrappy or planned. If planned... then I really wouldn't worry about "stash", I would just buy for each project. If scrappy, then consider what kinds of fabric you are drawn to: historicals, florals, bold colors or soft, modern or traditional. At this point, you can start choosing what to buy based on what you like. And I would start with some basics or blenders, because then you can add "focus fabrics" as the mood hits you.
My point is, that your stash should include fabrics that you like and actually will use. Personally, I don't like orange and so my stash will never have much of that color because I would not enjoy working with it, or seeing it on my bed, table, or walls.