Going shopping is for every woman a very pleasant activity. And, in order to remain that way, you have to be dressed accordingly.
The most appropriate outfit is obviously a relaxed one. But because you like to be trendy, you have to enjoy wearing your outfit.
When you go shopping, you have to be dressed lightly in order to be able to try n clothes more easily. For example, you can wear a pair of jeans, a cardigan and a pair of sneakers. Avoid as much as possible wearing boots because you will have to stand and walk a lot. Because of that your feet will swallow therefore it would be best to wear a pair of comfortable sneakers. Also, avoid as much as possible skinny jean, a pair of larger ones would be better. Another choice, maybe even more comfortable can be a skirt.
It would be recommended to give up on accessories. Having in mind that you will try on many clothes, the accessories will make you feel uncomfortable.