practise - every time I play whether at home or at a 'gig' it's practise and hopefully the more you play the better you become..... after 40 years in "the business" I would never claim to play or sing any number perfect.... and nobody I've known in the industry has claimed that... cast the first stone if you dare :-) - think of all the hours of retakes in the studio to get an acceptable "keep".
Be the best you can at the time and learn from your mistakes keep learning (even the "old stuff") and keep practising... and one day you may play something you feel at the time can't be bettered - make a note of the time and date - and the colour of the moon :-)
Pete