Volleyball is one of those sports where the score can look calm, then one small run changes the whole feel of a match. I try not to read odds movement first, because if I do that I start guesing too much. Scores first, odds second.
For a quick match check, I usually open Flashscore volleyball and Sofascore volleyball. Both are useful for seeing the set score, recent points, and whether a team has started badly or just had one bad rotation.
Official pages help too, especially if I want to understand the competition instead of only staring at live numbers. Volleyball World is good for bigger events, and CEV is useful for European competitions.
After that I compare the market pages. OddsPortal volleyball and BetExplorer volleyball are the two I check most often. I like seeing whether the price moved because of the match score, or because it was already moving before the set started.
My simple routine is to check the live score, then the set pattern, then odds comparison. It is not complicated, but it stops me from reacting too fast when one team has only had a short bad spel.