Falsetto is good for the voice if you don't strain. You need to approach it through head tones, very light and have plenty of breath support for it. It requires quite a bit of breath
to carry it. The most important thing is to approach it in a relaxed way and don't push.
You can really wreck your voice if you do.

Pete Seeger's approach to Wimoweh may have done some damage but there are plenty of yodelers out there who can do this without hurting themselves.

Falsetto requires the same vocal technique as the usual regular approach. Vowel placement and breath support with aid from a good teacher can help.

Try not to break your voice between registers when singing chest or head tones and then go into falsetto from there.

Frank Hamilton