This is a big question, and you will get very different answers.
If i am going somewhere unknown, i will usually wear wetboots, which look a bit like trainers with a built in wet sock, then i can get wet and change in the car.
If its somewhere with a known depth of water, or over CWD, i will wear waders. However, on 2 occasions now i have gone beyond wader depth, and the extra weight with all the water makes it very difficult to walk, and potentially unsafe. Rolling onto yor back to empty them just soaks the rest of your upper clothing.
So then, prepare to get wet, unless you know the water depth (but bear in mind water levels fluctuate) then dress appropriatley. 🙂