
My Grandfather was an elder in the church and a JP for Banffshire.. Hia father George Garden was a farmer at Rannachie and other farms in the area. His father John was also a farmer and had a fish curing business. I have seen the wills and testaments of George and John.and also birth, death and marriage records. Johns father was also called John but there are no parish records I can find.
Parish records tend to be very incomplete going that far back although spellings were very variable so you may find something using wildcards etc. There will be few personal records for ordinary people unless they are recorded in the kirk session minutes, court records, they or the farm are mentioned in land records, or they are mentioned in business records. I already suggested Aberdeen archives (various), Ordnance Survey name books, Canmore. You can search on SCAN, the NLS online archives, newspaper archives. You will probably need to build a tree including collateral family as there are thousands of Gardens in the area and you will need more than the surname line to establish where they fit in. I can't really recommend aiming to find a connection to a titled family. I can recommend contacting the Aberdeen and North East Family History Society.