Private music lessons with a good teacher can be very beneficial and get you off to a good technique and good habits right from the start. Furthermore, an experienced teacher can give advice about all sorts of things including making adjustments to your instrument to make it more playable.
An instrument that is well set-up can be easier to play and that is a very important consideration at the beginning of your learning experience.
Of course there are many videos and lessons online that are excellent and free as well as many courses that charge a fee. Whatever you choose to do, becoming a very good player takes a lot of time and effort and the best progress is made with regular practice on a daily basis.
There is no short-cut if you want to learn to play a musical instrument but the quickest and best way to learn is to get some lessons. Whether private or an online course, doing it right from the beginning is the only way to be successful as a musician.
Instrumental Lessons for Children
If you are able to get lessons at school it can be very useful. The standard of teaching is usually very good and the cost is often subsidised. Also, the opportunity to play with others in an ensemble or orchestra is a great advantage to developing musical skills.
Instrumental Lessons for Adults
The two main disadvantages in learning to play a musical instrument as an adult are, finding the time to practise and having the right attitude. Many adult learners are under-confident and are much more critical of themselves than children are. This means that instead of feeling positive about making progress, adults often dwell on their mistakes and try to run too fast.
So, have realistic goals and be kind to yourself ... you probably have a lot more potential than you realise!