Ah...sorry...I kind of skimmed, so I may have missed if someone said this already... (In a rush, but really want to give advice before I forget to)
Stores will not kick you out for buying women's clothes. Crossdressing and ->-bleeped-<- is generally considered an obscure thing, it's much more practical to assume that there's someone being shopped for or something. I think a store typically minds its own business if you want to try it on, too, but I am saying this specific 'I think' with also having a lacking experience of the darker side of society against TGs and non-TG CDs.
The worst thing you can do is be paranoid. There's no reason to be suspicious unless if you have a suspect. Just buy them in as casual of a way as anything else, and to feel safe, just have an idea in your head rehearsed. (Simply along the lines that you're shopping for a friend, maybe one that doesn't have a job anymore or something. You seriously should not need to get into details, and they have no right to ask anyway)
Hope that's helpful ^^