Most of the time, I spend very little time shopping for clothes. I have been known to pull something off the rack and buy it without trying it on and have it work out fine. Get "Metamorphosis" and figure out what shapes, colors, etc. work for your coloring and body type. Expect to spend some time up front trying on a lot of clothes so you can develop a mental model. Afterwards, shopping will get easier. You will be able to look at a rack of clothes and say 'wrong color', 'wrong shape', 'no..no..no..yes, I will try this one thing on'. Most of the time, the first thing I try on is the best thing for me to buy because I can pick it out so well.

With regards to comfort: For me, cotton, nylon, and silk are good materials. I am okay with rayon. I avoid polyester like the plague, which is hard because so many things are a cotton-polyester blend. I wear a lot of knits, something men generally can't get away with for a business look but something I find is wonderful in terms of comfort and a woman can it wear to work. I'm just careful to get the right weight of knit material that works for me/my look. That will differ from person to person.

I don't get your remark about making people take you seriously. Do you mean the sales people?