When I started playing jigs, my default bowing pattern made a groove like Pop Goes the Weasel: "Long-short, long-short, muberry bush, the long-short, long-short weasel."
And that still works for me without having to think about it. The one rule to keep in mind is: Do not slur from one string to another. This is unlike Irish reels. There, you can and do slur from one string to another. But not in jigs.
Getting the hang of ornaments
I think of the Irish fiddle ornaments as falling into melodic and percussive categories.
The three most common melodic moves are, the grace note, the triplet, the roll. These moves all use "neighbor notes." Any note within one step of the main melody note can be a neighbor note. In Irish fiddling, the neighbor note can be two steps away.
Grace notes are typically the upper neighbor, one whole step or half step higher. The grace note is usually played just before the beat.
In standard music notation it is shown as a very small note. In my tab charts I follow this convention by making the tab grace note much smaller than the main melody notes.
Triplets start with the melody note, go up to the neighbor note, and return to the melody note. The rhythm of this is a substitution of three internal beats for two.
Think of a shuffle pattern: dah-duh-duh. Now go: diddally-duh-duh. This ornament is very popular in Texas Contest style also.
The roll starts on the melody note, goes to the upper neighbor, back to the melody note, then to the lower neighbor, then back to the melody note. When the melodic note is played with the first finger, the upper neighbor is usually the third above, and is played with the third finger. In the roll, the neighbor notes are very light and quick, almost ghost notes.
Percussive finger and bow tricks
These next two moves are a lot of fun. They imitate the bodhran drum. I think of them as being rhythmic ornaments, not melodic.
The bow shake, (my term), is not intended to make three distinct notes. You should hear an interruption of the melodic sound when you do it.
Yes, it is a triplet pattern, but done so quickly that you just hear the sound of the bow digging into the string.
Finally, the cut, which you execute by dragging your finger across the (usually) open string without changing the bow direction. This also creates an interruption of the melodic sound. The violin as a percussion instrument!
Slidin' and Squawkin'
The first collection I found of Irish and Celtic tunes, way back in the day,was
English, Welsh, Scottish & Irish Fiddle Tunes by Robin Williamson.
This was published in 1976 and came with a vinyl recording of the author playing his tunes up to speed. I still play Carolan’s Concerto and Off to California, which came from this book originally.
Williamson writes about slides as being squawks and smears. A squawk is a quick slide and a smear is a lazy slide. The lazy slide has become a favorite of mine, often replacing several notes of a melody.
In slides the object is to start the slide flat to the target note. It can be a half step low or, sometimes, even more. When you slide up the neck, be sure to stop at the desired pitch.
Many times in my studio I coach students to do this correctly. The common mistake is to start at the target pitch and slide up. Be very careful to avoid this error. It just doesn’t sound right.
Quick slides, or squawks, can be done often. You will find some notes are better than others for a quick slide. The third note of the scale you are in, for example, is almost always good. The note attracts a slide, especially if it does not go by too fast.
The slower slide, the smear, will often take more time than the usual note allows. So you just steal time from another note. Then you take that note out back and shoot it. (Just kidding. You let the note back in later, when you don’t play the smear.)