I'm assuming that you have in mind the wearing of the ubiquitous short sleeved polo with shorts. If that is the case, then it does not matter whether the shirt is worn tucked or untucked, it looks geeky, rather like matching one's tie and pocket square. Better balance/contrast is afforded by wearing long sleeved shirts with shorts. Depending on the style and length of the shirt tail, in or out can look good. And, counterintuitively, the long sleeves can be rolled up and not spoil the effect. As for footwear, everything from the lightest of sandals to the heavyest of work boots can look terrific with shorts, dending on the style and weight of the shorts and the purpose for which they are worn. Boots, however, must be laced not pull-on. I commend to you, Ralph Finnes character, Count Almasy, in The English Patient, as the exemplar extraordinaire of shorts wearing.