Genealogy in Scotland
Family historians in Scotland enjoy many advantages over genealogists elsewhere. Some of these can be put down to the Celts' particular interest in their ancestors - which has resulted in so many of our surnames being patronymic in origin (i.e. those beginning with "Mac/Mc" meaning "Son of"). Examples are the extra information to be found on our Statutory Certificates of Birth (date and place of parents' marriage), Death (names of deceased's parents), and Marriage (names of both parents of the parties being wed), and the retention of wives' maiden surnames on most records and gravestones. Others advantages however are simply the result of a small population and the early centralisation of our basic records (OPRs, Statutory BMDs, and Censuses) which has allowed them to be indexed, filmed, and now digitised, ahead of most other countries - and, with the advent of the internet, made available to Scots descendants all over the world via the Scotland's People Website.
            Scotland's People not only gives access to all the records held by the General Register Office for Scotland [GROS] but also to much of the most important genealogical material held by the National Archives of Scotland [NAS] - particularly wills, testaments, and inventories - and the records supplied by these government bodies are supplemented by the work of a network of genealogical and family history societies who are cataloguing burial grounds around the country and recording the Monumental Inscriptions [MIs] found within them. The Scottish Association of Family History Societies [SAFHS] have published the nationwide list of burial grounds, and copies of locally recorded MIs are available in Edinburgh at GROS, the National Library of Scotland [NLS], and the Library of the Scottish Genealogy Society [SGS] - which also holds an extensive collection of family and clan histories from all over Scotland.
            Since there are many good books providing basic instructions on researching Scottish ancestors (see below) it's only necessary here to emphasise certain points that experience show to be particularly useful - especially for the descendants of Scots emigrants seeking their roots back in the old country.
            Firstly, because given names in Scotland were usually handed down from generation to generation the same names keep repeating themselves in families; so you must discover not only the name of your [emigrant] ancestor, but also as much incidental information as you can that will distinguish him or her from others bearing the same name (obviously the more common the name the more important that is) - particularly dates of birth, marriage [and if it applies, emigration].
            The normal pattern of forename transmission was: First son named for father's father; second son for mother's father; third son for father; subsequent sons for uncles etc. on each side of the family. First daughter for mother's mother; second daughter for father's mother; third daughter for mother; subsequent daughters for aunts etc. on each side of the family. Though this pattern was normal in some families it was reversed, and different families had different ways of dealing with the situation where the father and his father, or the mother and her mother, had the same name. Be aware too that some children might be named for other significant figures in the family's life - the minister, the laird, or the employer for instance - but virtually all were given for somebody significant and the idea of choosing a forename just because the parents liked it was entirely alien to most in Scotland before the mid-20th century. 
            Secondly, though your ancestor may be remembered and recorded abroad or in later years with a middle name it's highly unlikely that he or she would have been baptised with such a thing in Scotland before the late 19th century - unless he or she was a member of the aristocracy. It was common however in the 19th century - and occasionally earlier for emigrants - to adopt a middle name in later life, and this name was almost always also a family name (so probably a vital clue to the name of some ancestor).
            Thirdly, though you will hopefully find your ancestor recorded somewhere (censuses, gravestones, military records, passenger lists etc) with ages from which you can calculate a date of birth, be aware that before the middle of the 20th century - and the advent of bureaucrats always wanting to know our dates of birth - few people knew exactly how old they were, so ages must be considered approximate, and consequent dates of birth inexact.
            Fourthly, though you and generations of ancestors outwith Scotland may always have used one particular spelling of your surname, be aware that in Scotland itself spelling was not generally a concern until late in the 19th century, and it's almost certain that some - and probably many - of your ancestors before that will have spelt the name in a variety of different ways (and the longer, the more complicated - and indeed the more Gaelic - the name, the more variations there will have been). This especially applies to Mac... and Mc..., since the latter is just an abbreviation of the former and, contrary to the Scots v. Irish myth, is the most common form in Scottish records.

Books on Scottish Genealogy:
Kathleen B. Cory, Tracing Your Scottish Ancestry (Edinburgh, 1996; Baltimore, MD, USA, 2004).
Alwyn James, Scottish Roots (Edinburgh, 2002).