Belting

Good day , I watched the video about belting and I want to ask for my safety : is it good to only rarely use my belting chest voice to avoid damage or I can use it more often once I get better 

Hi, Darick! The ideal is that you're bringing in some "mix" most times you're belting. If you only use chest voice, your range will be limited and it'll be more tiring for your voice. So for a "full chest" sound, use it in moderation, and make a "balanced chesty mix" your default. See below for some resources on how to do that!

First, make sure you're exercising your head voice! Those head voice muscles (CT) need to be working. Use a full-range lip trill or OO to let your voice "hand over" from chest to head. As you train your chesty mix, that "hand over" will just be more gradual, with less head voice.

In that middle/mix range where you're starting to feel strained, try using a tall + narrow mouth position (OH or UH shape, rather than a wide HEY or YEAH shape) to encourage more mix (head resonance along with chest). This will relieve some pressure and help you avoid the unstable "shouty" pulled-chest voice sound.

Here's a video with a singer using that kind of "tall and narrow" vowel modification: https://www.youtube.com/watch?v=BVqS_BYsDBA. Listen carefully to the tone after he modifies the vowel. It goes from shouty chest voice to a strong but more balanced "mix". 

Here's an article on the kind of vowel substitution he used as well: https://www.thenakedvocalist.com/quick-fix-vowel-substitution/.

These are the 3 exercises I like best for stretching chesty mix: https://www.youtube.com/watch?v=qwiwZ3dS8mg&t=408s

Here's a short lesson on avoiding "flipping" within mix: https://www.youtube.com/watch?v=6pI9v1YMFN4

If you're getting a shouty tone, here's another lesson addressing problems with mix: https://www.youtube.com/watch?v=vzObbNv78oA.

I also love this teacher's demonstration & explanation of mix: https://www.youtube.com/watch?v=pYsO7HX84P8. 

Lastly, remember that you're building coordination (between your TA and CT muscles) while you stretch (CT) and continue to resist air (TA). Progress might be slow, but keep at it!