On approaching Moustiers, and realising its wanting to be a pedestrian town and keep the traffic from the hordes of visitors - particularly in the summer months when apparently tourists visit in droves - out of the town centre by providing large parking areas on the outskirts a few minutes walk away, you will get directions and options of a parking area on your left as you arrive or taking a turning to the right up hill a bit.
I parked to the left which was convenient and only about 5 minutes walk to the old centre of this beautiful hillside village - but since found that if Id taken the options to park up on the right itd be much closer to the uphill path to the church which is high on the hill above the village and also closest to the village centre.
Both parking areas would be wheelchair friendly with a sloping ramp pathway up from the car park to the next street above (also where very conveniently public toilets are placed).
Nestled below beautiful mountains on the far side of Lake St Croix from the wonderful drive through the Gorges and Grande Canyon of Verdon is beautiful Moustiers and what a lovely drive it is - so the best way is to go by car so the ability to take photos from the windows or stop when and where you want are not inhibited or restricted - such as might be by public transport!
Also like me going independently by car allows your own schedule and you can fit in more and less according to your own whims and not have to rely on any public transport schedule that out in these more remote locations may be intermittent or few and far between.
I drove to Moustiers aware that I only had about another hour or two of daylight so I had to hurry a bit but at least I got to see lovely Moustiers and then rush off and catch the Night parade of the Carnival in Nice which is only an hour and a half away.