No one is born with any natural talent to play an instrument. Learning to play an instrument is only a matter of how well and how often you practice. The more often you have a good practice session, the faster you will progress at playing your instrument. This becomes a positive feedback loop - the more you practice the better you will play and the better you play makes you want to practice even more!
How much practice will you need:
Beginning players - Try for 30 minutes a session and 4 sessions a week
Intermediate/Advanced players - Try for 45 - 60 minute sessions, 4 or more sessions a week
Professional players - Several hours almost every day
However ... Even practice sessions as short as a few minutes can be helpful if they are targeted to very specific goals.
Find a quiet place to play where there won't be distractions
Try to practice in a quiet space where you can clearly hear how you are playing. That means don't have the TV, music, or the latest podcast on in the background.
Through practice you are not only learning how to play your mt dulcimer you are learning how to listen to the sounds you are making with it.
If you are reading music/tab, set your music stand to the side your fretting hand is on. This allows you to see your fretting hand AND your music at the same time without having to move your head too much. This helps keep you from losing your place in the music.
Before you begin stretch fingers, hands, neck, shoulders, and back
Since your brain can't learn anything when it's anxious or stressed, it is very important for you to be relaxed!
The first song(s) you should play is one you like and that you play reasonably well
Spend a few minutes each practice session working on left and right hand coordination.
While strumming or picking with one hand, play random notes/chords with your fretting hand (this is specifically not practicing a song) Try to watch both your hands at the same time while you do this. Remember, for smooth playing, your transition from one note or chord to the next with your fretting hand has to be fast but your strumming/picking hand has to stay with the same rhythm. Essentially, with your fretting hand you want to hold the note or chord for as long as you need to until quickly moving to the next note or chord and at the same time with your strumming/picking hand you want to keep a steady beat. (At first, it isn't easy to do two very different things with your hands at the same time!)
If some aspect of your playing isn't quite working for you, practice that aspect specifically and very slowly for a few minutes.
If your strumming isn't as steady as you like it, just strum the open strings for a few minutes.
You can also practice strumming when away from the dulcimer by strumming against your leg whenever you hear music with a strong beat.
If your fretting hand seems to be getting tangled up, just fret random notes using different fingerings.
You can practice fretting when away from the dulcimer by pressing the fingers of your fretting hand down on a table pretending to follow the tune as you hum it or let it play in your head.
When you do practice songs ...
Look at the tune before playing it to see if there are any small sections that repeat
If you are not familiar with the melody, play just the melody without the chords to cement that in your brain
Find the sections that you think will be difficult to play
Try different fingerings to see which will work
Practice small sections in isolation even if it's just a few notes. Play so slowly that it's impossible to make a mistake
Once you've played that short section, back up a measure in the music and play through that section and onto the next measure a few timesAlways sing/hum the song either out loud or in your head as you play it! This cements the tune in your brain and helps when you try to get the tune to come out your fingers on the dulcimer. It also helps to keep your mind from wandering and causing your fingers to wander too.
Play the whole tune much slower than you think you should.
Once you are playing the song slowly without making mistakes, begin to increase the speed of playing the tune.
It can also be helpful to alternate between playing slowly and playing faster for a whole song or a section of a song
After practicing songs or in between different songs, spend some time just "noodling" around. Play random notes and transitions and see what sounds good to you and what doesn't. (You just want to experience the joy of the musical sound without worrying if you are playing a particular song correctly. )
Spend a few minutes practicing scales, finger dexterity exercises, etc
End each practice session with a song you like and that you play reasonably well (it's fine if' it's the same song you began with!)
At the very end, as you are putting away your dulcimer, take a moment or two to experience the joy of learning to play your dulcimer!
Some people like to record all their practice sessions. If you can do that without getting distracted by other things on your device it can be helpful. But - you probably don't want to listen to those recordings right away. Instead record them over 4 - 5 sessions of playing the same tune, then, not during your practice time, listen to the progress you made between the first recording and the last one. However - be honest with yourself! ... How much time are you spending of your precious practice time just fiddling with your phone trying to get it to record. Or how much are your criticizing yourself and your playing when you listen to the recordings! If you are playing with your device too much or criticizing yourself too much, recording your practice sessions will be counter-productive to making progress.
Don't worry if you think you aren't making progress. Just keep practicing. You won't notice the progress until you can look back after a long while (months at least) of consistent practicing.
Don't criticize yourself! Learning to play an instrument is very frustrating and de-motivating. You have to power your way through that. If thoughts like "I'll never get this" come into your head push them aside and just keep practicing. Seriously, you are getting better even if it is so slow you can't tell from one day to the next.
If you don't already sight read musical notation (the music staff with notes) don't try to learn that while practicing your dulcimer
This may seem counter-intuitive but ... please believe me ... trying to read the music while also learning a tune is a distraction!
Reading the notes won't help you learn to play them on the dulcimer. Instead focus on the song and try to play the song not the notes. You can do this by singing or humming the song, either out loud or under your breath, while playing the numbered tab.
If you don't know how a song goes you won't be able to figure that out from the musical notation unless you are an expert at sight reading music. Instead, find the song in youtube and listen to it over and over again until the song is in your head.
If you want to learn to sight read music, do that separately from your dulcimer playing practice. There are many, many books and resources online to help you with this.