Gabi … you get there by shooting a LOT, but also by carefully considering your direction of light from your flash, and the balance with the ambient light.

Here are two articles to start you off with
flagging your flash vs simply bounce flash,
bounce flash examples at wedding receptions

Neil vN

First of all, beautiful work. I have a question…the most difficult shots, I find, are the ones like the 15th you posted (groom behind bride on the dance floor). Every time I try this shot, it is on pure faith that the exposure and flash will come together to get a result like the one you took. Furthermore, I don’t even know how to practice trying to get this shot. The result – sometimes a winner but often a shot that is way off balance in terms of exposure between the foreground and background (many stops…much lightroom correction).

My question…how have you trained yourself to consistently take solid on-camera flash reception shots?

Sincerely,
Gabi