Both vocal technique and training are essential for a singer. However, good vocal technique should be the basis. Even if you already have a good voice, a qualified voice teacher will help you develop your voice even further. And a vocal coach will make sure you're ready to perform.
It's one of those contradictory things. If it turns out that you have many advantages that make singing quite natural, such as a good ear, a lot of musical exposure as a child, and a good sense of your own voice and body, then it may seem easy to learn to sing without formal instruction. For example, having prepared specific songs with a vocal coach and having performed exercises that explore tones that far exceed the highest notes of the song will reduce the likelihood of anticipating the high notes and forcing or falling flat on those notes. The vocal coach can quickly identify weaknesses and problems in a singer's approach, but he also has the teaching expertise and experience that allow him to skillfully guide the student toward development by applying practical solutions.
Okay, it must be said that one of the best ways to improve your vocal skills is to hire a singing teacher. All you need to do is take the initiative to step up and learn everything you can until you can hire a vocal coach. Some people have grown up singing all their lives, while others have the option of paying for a vocal coach. However, others of us don't have the option of paying for a coach, either because of a lack of vocal coaches in our area or because we simply don't have the financial capacity to pay for classes.
With proper vocal technique and proper vocal care, the concern of damaging the voice will significantly decrease.