These practice tips were written for fiddlers. I've used them in classical violin also. You will find they apply to any music learning goal you have set for yourself.
Learning new repertory raises your instrumental or singing ability. It makes you learn new combinations of notes. It takes focused effort and stretches your comfort zone.

Be sure you know what the piece sounds like. If you can "kind of" sing along or hum along with a recording, that’s a good start.

With any chart, whether standard music notation or fiddle tab, there is a first time you go through it. In music it's called sight reading. It's a skill that can be learned with practice.

In the folk music world, it is not a crucial skill. The point of having a chart is simply to help you get started easily.

Visual learners pick up a tune most quickly with a chart.

When I go through a tune the first time, I might miss a rhythmic figure, or a note here or there. Then, the second time through I'll slow down on the tough part and figure it out.

Once you've played through the new chart a few times, you know where the traps and difficult spots are.

A trap is a place in the music where you were surprised by the choice of notes. You expected something else, based on what you were playing. You got blind-sided by the actual notes.

You can lock down a trap by a practice tip I call "the slow down technique."

What you should not do is what most learners do until they get some coaching. You play along at a normal speed, hit the trap, and, oops! Back up and play it correctly, then keep going.

This is a good way to train your brain to fall into the trap.

Better is: simply slow the tempo as you get to the tricky part and play it accurately. Speed up to normal after you get past it. Repeat as needed. This way you are putting the trappy part into context. You are letting your brain connect the dots.

The other way--oops! and fix it, will work eventually. But it’s so inefficient. Instead, allow your brain the chance to learn a new pattern of notes. They’re not so difficult. They just go together funny. Slowing down enables you to play the part accurately. This is just crucial.

Truly difficult spots require you to do something with your hands, or voice, that is definitely awkward.

You need to focus like a laser on exactly what is the difficulty.

"Let's see...I have to hold my 2nd finger down while I reach with my 3rd finger to the next string, while slurring with the down bow, then...."

Be very aware of exactly what problem the awkwardness is creating.

Some spots require several tough moves, one right after the other. Such a spot may require three or more seconds at first. Repetition builds speed naturally. You are creating and strengthening pathways in your brain.

Your goal should be, not so much getting faster, as getting easier and smoother.

Remember this universal musician’s rule. You are allowed to mark your part with a pencil.

Sometimes I’ll just draw a small wavy line above a trap or a difficult spot. It helps me to focus in my practice.

When you have isolated the most troublesome spots, play or sing each of them correctly three times in a row. This is the most basic practice technique of all. Make it your default habit and see your ability move ahead.

After spending some time with these techniques, you are ready for honest self-evaluation. Play through your new tune at a slow enough speed that you can play or sing all the hard parts accurately.

In other words, use a steady tempo that allows you to play with zero errors. Using a metronome, take note of the exact speed. Write that down on your chart as a benchmark.

Later, you’ll be pleasantly surprised at the increase in speed with accuracy. This builds self-esteem and the habit of constantly getting better as a musician.

In tunes that have running sixteenths--notes that keep changing four to a beat--use four distinct rhythms to get mastery.

This running sixteenth note pattern is far more common in instrumental than vocal music. But, then, there’s Mozart.

Go through the passage with a swing feel. Taah-tu, taah-tu, etc.

The second rhythm is strathspey. Each pair of two notes is played quickly on the first note and longer on the second. This is just the opposite of swing rhythm. Tuh-daah, tuh-daah. etc.

The next two rhythms involve grouping four notes as one beat and a triplet beat. Tum, ta-da-da would be a beat followed by a triplet beat. Ta-da-da, tum is the triplet beat followed by the single note beat.

Just a little rhythm practice on a running sixteenth note section of music does wonders for cleaning it up.