Both up river and down is good. It really depends on the area. Trolling down river in the rocks or logs you better be on your A game or you will donate a lot of cranks.
Also trolling down river you do not need to speed way up. Most of the time I slow way down. Kick the motor in and out of gear to just move a tad faster than the current. This will drive the lures down to the bottom in a hurry. You also shorten up the amount of line you have out running down river. Even with this i would get the hang of trolling up river before trying down.
Dont worry to much about loosing cranks while trolling in the river. Its going to happen. Find good cheap cranks like the flicker shad or smash shads and buy a lot when on sale. Im not to heartbroken if I loose a half dozen $3 cranks in a day. Thats about the same price I would’ve spent on live bait or maybe even less depending on what the bait is.
If you get snagged up drop your line back right away to create a little slack. Many times this will float th crank up out of it. Next get below the crank and try pulling it out the opposite way it went into the snag. Third point the rod tip at the snag, grad the spool and hold tight while pulling the line. Its either going to come out or snap off. Either way its time to get back to fishing.
Running a line like 15 or 20 power pro will help with getting lures back to. 10# is to light.