[TBman]

I'm not a musician so this is what I do. (None of this happens overnight, btw)

Find a tune you really like and the tab/notation that matches it. Check out Homespun for their Celtic fingerstyle lessons or do a search online for something similar. Play along with the original artist/instructor and learn to mimic what they do.

Once you get as close as you can to the way the original tune is played you can start giving your own notes a life of their own, but you have to stay within the flow of the tune. Sometimes you have to alter the arrangement a bit to do what you want to do.