Particularly for violin players…
You will find that in the world of traditional music most notation has no dynamics printed on the page. This doesn’t mean everything is played legato at the same volume all the way through with no slurred notes. The musical notation you will come across is intended to be used by players of all instruments and we add the stylistic dynamics specific to the instrument being played.
Traditionally these tunes are played for dancing and the melodies are played with a strong accent on the beat (to give dancers an audible cue). This is usually achieved by playing the accented notes with longer bows than the quieter notes. (longer bowed notes will force you to move the bow faster which requires a bit more weight on the bow) Essentially we add the dynamics and ornamentation as we see fit.
The written down notes are just a guide as to how the melody goes, not how it should be played. The more artists you listen to, you will notice they rarely play a tune exactly the same twice in a row, this music is full of variations and alternative ways to express the melodies (this aspect of the music usually can’t be found in any notation, it’s the personal touch we add to the music)
NO VIBRATO!! You just don’t hear it in Celtic music at all, (maybe on the final note of a slow air but that’s it).
First position ONLY. Practically all Celtic music fits within the scope of first position.
OPEN STRINGS are always the preferred option. You will generally only use your little finger to play B’s on the E string or embellishments on 3rd finger notes of on other strings (Scottish fiddlers sometimes like to play a unison 4th finger with open strings to add a drone effect).
If you find a score by some orchestral composer called something like “variations on an Irish jig”….. no one at any session is ever going to know that piece of music and join in.