Pack some comfy that is not too tight, as Uganda is in the tropics and the weather is generally hot and humid. Stay away from blues as they tend to attract tsetse flies especially when you are out on a boat ride or game drive. It is pretty sensible to pack long sleeved shirts as they will protect you from severe sun burn and insect bites. Some parts of Uganda can be really cold like in Bwindi, it is smart to pack some light jackets or sweaters but avoid camouflage because in Uganda it can get you arrested. One more essential to wear is a backpack to carry all your valuables and snacks you will need.