If you’re thinking of following the loop its better to follow it clockwise, as it will flow better.
Aviemore to Tomintoul is reasonably straight forward. There is one river crossing, but its fairly tame. Theres also one bit thats not very clear on the map, but reasonably clear on the ground.
Nothing to worry about on the run between Tomintoul and Braemar.
Theres a defined track once you leave the double track after Braemar, which will take you to the bridge. The bridge is fine (it looks a bit wonky though) or you can ford the river further down stream if you wanted to.
The bridge at Carnachuin doesnt exist, but you theres a good track on the eastern side of the river until you get to the road at Achlean.
Go early if you can as Midge season will be in full flow late July