Find the really tricky bit, find the TWO NOTES that are really causing the problem.
Play those two notes more and more SLOWLY until you can play it correctly.
Now carefully look at the note before and the note after the TRICKY BIT.
Once you can play those as well, add the notes before and after until you have done the bar before and the bar after the TRICKY BIT.
Take your time to find EXACTLY where the tricky bit is.
Be CAREFUL! Only add the extra notes when you are SURE there is no glass in the sand for Careful Crab to step in