I've had some limited success with Scottish and Irish accents just from watching movies, really. Granted, I'll often start in one and end up in the other XD .
Oh, guess my own dialectal background would be good *ahem*. I'm from the American west coast--grew up in the crap-hole state Nevada and later moved to California. This means that my accent can range from near-southern/very "redneck" to pseudo-surfer, depending on who I'm with, how tired I am, whether or not I've consumed alcoholic beverages in the last two hours, or what accents I've heard recently. These are my "grew-up-with" accents, I suppose. Being one who makes a hobby of learning and imitating accents since the sixth grade has made my daily speech actually quite more variable than I've so far described. I have days where, within a span of fifteen minutes, I will sound: Parisian, Texan, Georgian (state, not country), Missouri, New Yorker, Boston, Brooklyn, British (London--North and South), Manchesterian, Australian, Mexican, Spanish, Russian, and something that vaguely resembles Norwegian (I think).
It's a lot of fun for me, but most of my friends get rather irritated by it. Half the time I'm not aware of it XD .
And that's not all of my repetoire, either XD .
And where did I learn all of these? Mostly... movies. Which aren't quite 90% reliable, but usually give you a good idea to compare to a native accent on an actor you know REALLY has said accent or someone you meet in real life with said accent. Actually, the first accent I learned was London from the movie "Austin Powers". I can safely say I've progressed significantly since then, so don't worry o_o; .
Scottish and Irish can be hard, though. They have a lot of similar vowels, so the big difference, at least to my ear, is in stress and pitch. It's sort of like listening to American English and then listening to Carribean English--the stress, pitch, and even cadance are just off from each other. At least Carribean is easier to isolate the differences ![Stick out tongue [:P]](/emoticons/emotion-4.gif)
. Anywayz (yes, I used a z >_< ) , that's why I always start Irish and end Scottish or the other way around. I start confusing Boondock Saints with Braveheart and then *death*. There are just similar enough for it to happen, but not so similar that I'd be easily confused if I heard them--though that can happen, too (to my dismay). There aren't enough movies with these accents in them >_< . My best resource has failed me T_T .