hi Robert
Underfoot, the Machar Pool can be very silty. Disconcerting when your wading boots disappear into the mud. Don't panic. It is safe enough. However I would recommend going at low tide first just to have a good look at the channels and where the mud/silt is, and also where the main river channel flows. It has been a few years now since I've been there, but here's some pointers from memory.
The parking is on the north bank. Arriving at the water edge, take a right and there is a wee bench. Most regulars fish around that part of the beat, probably because the wading is silty but predictable, and backcasts are clear. I was told that the lower end of the beat was useless, but since I did land a 9lb12oz ST from down there, i suggest you explore and find your own hotspots! I never had much joy further upstream from the bench, but it's fishable, although there is one dodgy bit with signs advising caution with wading due to an underwater pipe.
The main river channel runs straight down the middle, with a fairly clear drop-off (again, go at low tide to get the visuals); careful not too wade too far or you'll spook 'em. Or fall over the drop off... I suspect a rising tide is worth a cast; at low tides, the Pool gets mostly cut off from the sea estuary, so they say that the ST follow the outgoing tide and vacate the Pool. But they used to say the earth was flat too, so don't listen to them (and if the ST don't go out with the tide, they are trapped...).
flies/tactics? Usual ST flees, i guess. My best ST from there came on a size 14 pearly invicta. But then I always used to fish with that flee, so it was a bit of a self-fulfilling prophecy.
there's a map and beat summary on the ADAA pages at
https://www.adaa.org.uk/ythan and an active google map at
https://www.google.com/maps/d/viewer?msa=0&mid=1gAvfmctMhyxPkFOhFKqHMg79PAA&ll=57.398521358830635%2C-2.1450949999999693&z=12 cheers
iain
