I found these on the Uilleann Pipes forum:
Remember at all times: someone else can do it, therfore so can you.
Be patient.
Practice S..L..O..W..L..Y. Be conscious of what you are trying to do.
For those of us who learned typingin a classroom on actual typewriters, the axiom was to learn accuracy first and the speed will come. This is true of musical instruments too.
(BTW, I had to make four typo corrections before posting because I never really took to my typing lessons as I should have)
So true. I play the piano and no matter how fast you want to go, it’s best to take it slowly first.
If you learn it incorrectly the first time, it tends to stick with you and it’s a pain to correct it.
Remember that even the greatest players were once novices.
Even if you never get to Carnagie Hall, or The All Irelands, you will get better and better at something you love.
Perfection is a great goal, but a lousy requirement.
Speed does not equal ability.
There are many ways to improve - Intonation, finger dexterity, breath control, ornaments, scales, clearer bell note, sweeter high notes, cleaner half-holes, crisper changes, rhythm, speed stability, dynamics - there are myriad aspects to playing music well, and many ways to practice all of them.
One of the best ways to get better is to listen to those who already are. Surround yourself with good examples of the music you want to play. Listen to it actively, looking for examples of all those things listed above. Listen to it passively, as background music while you work, read, cook, exercize, or drive.
You can even listen to it while you sleep. Really! I have John Skelton’s “A Few Tunes” and :A Few More Tunes", and I frequently put them on to play softly when I go to bed. (my husband isn’t even jealous! 
) I have been quite surprised by my increasing ability to know what comes next in tunes I didn’t know I knew, and improvement in those I thought I already did.