hello UG ! sometimes i go out of tune while singing , and this when :
1 - i hit the first note then i return to the right tune ( not always )

2 - i play a song in another guitar tunning ( not always )

any help plzzz !
There are SO many factors that affect intonation.

Here are a few:
- Just like if you can't see a target before you fire, then you can't hit it, iff you can't hear the note before you open your mouth, you can't sing it.
-it takes practice controlling the voice in even the simplest of ways. Before I started voice lessons, most of the time, if you played a note, it would take me three attempts before I could even match the pitch. (funny, I was usually off by either a fifth above or a fifth below...)
-too much air (pushing the voice) makes you go sharp. (that's why you don't "push with the diaphragm")
-not enough air (poor breath support) makes you go flat.
-poor placement makes the pitch of the note sound unfocused.
-poor resonance makes the note - even if the pitch is fine - sound flat in terms of "being lifeless", which is often perceived as being flat in pitch.
-singing does have a lot to do with muscle memory. I know, for instance, what it *feels* like to sing the G at the top of the baritone range to a point where I can almost hit the pitch without a reference. Learning a song in a new key requires you to "re-learn" the muscle memory of those notes.

Could I get some more talent in the monitors, please?

I know it sounds crazy, but try to learn to inhale your voice. www.thebelcantotechnique.com

Chris is the king of relating music things to other objects in real life.