We have 3 important factors in santoor learning:
Obviously every branches of arts needs a minimum amount of talents and interests, although if someone with both of the abilities doesn't work hard, he wouldn't be successful.
Effort is a really important factor in learning a musical instrument. You have to work hard to be a professional santoor player. Practice at least 1-2 hours a day.
So if you have these 3 factors all together, after about a year you can play a piece of music nicely (not professionally). Being professional in santoor and Iranian music in total is a long process, you have to learn different branches of music besides santoor such as: Music theory, Solfège, Composing and…
All the things that we said was for the music students, but we also have a teacher part. In fact teachers have a significant impact on students. This impact includes teaching music, teaching creativity, increasing self-esteem, etc.
You also can improve your music knowledge and skills with listening to Iranian music albums and old and new tapes of different masters, going to concerts or watching them, being involved in music community, etc.
Consider that all the mentioned factors should be done together and you can't be a professional Iranian musician or santoor player, by doing 1 or 2 of them.