Living very close to Anglesey, ive walked most of the path, with just a few sections nearer Holyhead to complete the full 125miles.
Its only the Pentraeth, Benllech, Meolfre and Amwlch to Wyllfa power station sections that are moderately challenging, being quite undulating, but still very easy going.
I would start from Menai Bridge, and work your way anticlockwise, so that all the undulating sections are completed first.
Holyhead back to Llanfair PG and Menai Bridge, passing through Newborough and Trearrdur Bay, is mostly flat and easy going.
Its still a magnificent walk, and the sea life, can be pretty dramatic, especially off Bull Bay near Amlwch.