This is the speech of the Scots, those who live in the northern part of the island of Britain, more-or-less defined as north of Hadrian's wall.
Rhythm and Music
This dialect can be either very heavy or very delicate, depending on what is appropriate for your character. My usual trick for this dialect is to imagine that you have a rag in your mouth. The mouth is held more openly than in, say, Upper-class English. You can think of the sound as being generated either under the back of the tongue or in the space immediately above the back-most part of the tongue.
As a side note, in reality there are almost as many variations in Scottish dialects as in English. Highlanders speak very differently from lowlanders, to but scratch the surface. The dialect presented here is a sort of Generic Stage Scots, and should not be taken as representative of the speech of all Scots.
The Scots use all the standard tricks described on the dialect page, with just a few changes in vocabulary:
Scots tend to say "nae" for "not." So, instead of the word "cannot," the Scots would say "cannae." Similarly, "do not" becomes "dinnae," and so forth.
Instead of the word "understand" Scots use the word "ken." This word is also occasionally used to substitute for "know," as in "I dinnae ken where the fellow be."
Where an Englishman might say "lad" or "lass," a Scot will use the diminutive "laddie" or "lassie." A Scot might use these terms for adults, as well.
Scots will also use "ye" instead of "you."
Scots will use the word "wee" for "little" or "small."
Each of the links below is an ".mp3" file demonstrating a sound change. Listen to the example as many times as you need to, repeating it on your own afterwards. Take as much time as you need to with each sound. If you take the examples in order, you will sometimes run into sounds you haven't gotten to yet. Don't worry about it, just do the best you can until you've gone through all the sounds. Then go back and listen to the examples again, and make whatever corrections you need to.