my rule is, if you can't see the bottom (or rocks), go slow. other than that, make sure all of you connectors are the sealing type and they are fully inserted (check every prep). all high voltage circuit have to be sealed, even a little water will cause problems there. make sure there is a drain in your airbox, in case your get a bunch of water in your intake. intake should be as high as possible. vent tubes in your diff and transmission should be as high as possible, otherwise water gets sucked in when you diff/transmission shock cools due to cold water and the air/oil contracts, water from creeks and stuff is likely to have suspended sand/silt in it and will cause problems inside your diff/transmission.