From the south - Follow M90 to Perth, then take the A90 Dundee road and follow this up to Aberdeen.
For coastal route - as soon as you reach Aberdeen, follow road signs for A90 for around 18 miles, then turn off on the A952 to Fraserburgh. Then at Fraserburgh, follow signs for A98 to Banff and approximately 20 miles along that road, you will see the turn-off for Gardenstown.
For country route - follow roadsigns for A947 Banff/Macduff. At Banff Macduff, follow roadsigns for A98 Fraserburgh for about 2 miles until the signed turn-off for the coastal route and Gardenstown.
From west/north - from Inverness, follow the A96 Aberdeen road until a mini-roundabout near the end of Fochabers, when you turn off on the A98 Fraserburgh road. Follow this road, going through Banff/Macduff until you reach the signed turn-off for the coastal route and Gardenstown about 2 miles out from Banff/Macduff.