How to play King's Fiancetto opening

I want to try having my main opening be the King's Fiancetto but I don't seem to be playing it right. Whenever I play the opening, though, I seem to always end up in a position with my opponent having a considerable advantage. How do I play the opening?
Not a good idea to go fianchetto at the 400 level but I’ll entertain you being a hypermodern player myself with the white and black pieces.
Go 1.Nf3 to take away the e5 square which will make your development and life easier by transposition for the fianchetto set-up but more importantly, enabling you to fight for the centre or grab more central squares by following up with d4 or c4.
Its important to not give up on the centre.

Hi! I would not recommend you to play King's Fianchetto (either 1.g3 as White or 1...g6 as Black) because it requires good positional and opening theory understanding, something players start to develop at intermediate level and higher. Instead I normally recommend my students to play classic openings like 1.e4 as White.
But since you already like this opening, here my suggestion: play first 1. Nf3, then 2.g3, 3. Bg2 and 4. 0-0, so as to quickly develop your pieces and put your King to safety. Then counter attack on the center with d3 and e4 (King's Indian Attack) or d3, c4 (Reti opening). Of course in the middle check if black can disturb your devopement (for instance with ...e5 and ....e4).
Good luck!
I want to try having my main opening be the King's Fiancetto but I don't seem to be playing it right. Whenever I play the opening, though, I seem to always end up in a position with my opponent having a considerable advantage. How do I play the opening?