First thing you need to do is check with the ranch or guide you choose to hunt with in order to find out how you will be hunting. In other words will you be hunting "Texas Safari" style where most of your time will be spent in a air conditioned vehicle, stand hunting over a feeder where you will be in the shade most of the time and have very little need for a lot of physical exertion or will you be stalk hunting where the physical demands will require you to be in good shape and carry a lot of extra water i.e. weight on your person. It is very important that you are completely honest with your hunting guide about your physical condition. For example I have a friend who absolutely hates to hunt from a vehicle and refuses to sit still in a stand for any length of time, however, as he weights close to 400 lbs safari style hunting is the only way he is capable of covering a lot of ground without physically endangering himself. (He would probably have a heat stroke if he had to walk more than ½ mile in the heat and humidity we have down here.)
Next as the others have told you, wear light colored, light weight breathable clothing. Whether or not you have to be covered in camo from head to foot will be dictated by the hunting method you are going to use. For example when I hunt in a ground blind over a feeder I wear shorts and the lightest weight t-shirt I can find. As my body is hidden from the animals vision, color is of little concern. Conversely, when I am stalk hunting in during warm or hot weather I wear camo shorts, a camo t-shirt under my mesh leafy wear camo suit. This way I am completely covered yet my clothing lets me take advantage of what breeze there is.
Another thing to bear in mind is that hunting during the summer will eliminate some of the exotic species from your potential list of animals. For example, sika, fallow, red stag, elk, barasingha, pierre david and most all of the other deer species will not be in hard horn during this time of year. The exception to this will be the axis deer. With them the summer is the best time to take a good trophy as most of them will be in hard horn during this time. Also the majority of the blackbuck males will be in the lighter summer color phase now. That means they will not have the distinctive black coloring on the upper part of their bodies. Instead it will be more of a lighter reddish brown. As far as the exotic rams and aoudads go, they will have a lighter summer coat that does not have the heavy beards and chaps on the front legs that so many people look for when hunting these animals. You will also have to be careful and really look a ram over good before you shoot it because some of them will have a rubbed look to their coat that can make them look very unattractive when mounted. Same goes for the super exotics.
With all of this being said there are several operations that do still have quality animals to offer during the summer months. Just research the species you intend to hunt the best you can before going so that you will know what you are looking at through your scope before you pull the trigger. After all you dont want to find out that the trophy axis buck you just shot is only a 25 dink because you didnt study the species enough to find out that a 30 specimen is the bottom end of the trophy range or that a 30 main beam length with 15 caudal tines is probably an exceptional animal because of the mass and extra long caudal tines that normally run 7-8.
Good luck in what ever you choose to do.
