Avoid large designs and silk screens on the shirts that prevent the fabric from breathing. The North Face make nylon tek tees that dry in minutes and are very light. I brought three along on my latest middle east escapades and they served very well. Proper pants are very important, and for numerous reasons, shorts are not a good idea, especially for women. Long pants shade you better, and are much tougher if you are doing anything more than a tourist stroll.
Jeans are tough, but very heavy, take forever to dry, and are hot.
Khaki slacks are a much better choice. They are light to carry decently tough, cool, and look very nice if you buy the wrinkle-free incarnations. Nylon hiking pants are also useful, mostly because they dry so fast and some have zip off legs. Cargo pockets are a plus on any pants. Shoes are the most important gear item when you are traveling.