I was really nervous at first when going shopping with my mom, because she suggested I go wander off and find something while she looked at something for her and I couldn't find the right section. (We weren't on the right floor, so it wasn't my fault.)
But then we went to another store that had more clothes that I was interested in, and within a few minutes I was explaining to my mom what patterns wouldn't look good and which would, based on what would make my shoulders look bigger and stuff like that.
That was so much fun, and I felt pretty comfortable after I realized what I was doing. (Of course, between the awkward point and comfortable point, one of the women working at a store asked, "Can I help you ladies find anything?" while looking straight at me when I wasn't feeling especially feminine, so my confidence got boosted hugely.)
One thing that really helped was ordering a few clothes online so I'd have something to wear while shopping.
-----------------------------------------------------------
Oh, more self-indulgent news. Just two days after filling out my name change paperwork, I have received a letter addressed to "Ms. Emily (real name)" with three copies of the court order for my new name.
I'm not legally female yet, but I guess either they didn't know or they decided legal gender didn't matter when addressing a letter.