If you prefer to watch videos instead of reading the guide, feel free to do so. There is a playlist that covers an entire platinum playthrough on my YouTube channel. If you'd like and subscribe, it would mean a lot to this channel!
The first act ends when we are heading to Kivuli. Before going there we can already collect 13/32 Echoes, 4/11 Trinkets (You'll get the second trinket automatically when you use the first workbench), 2/6 Reflections, 1/3 Spirit Rituals (Important: Finish all 3 trials in order to get all trophies related to the ritual)
The second act ends when we enter the Deadlands. Until then we can find up to 22/32 Echoes, 7/11 Trinkets, 4/6 Reflections and 2/3 Spirit Rituals in total.
After the third chapter we have all abilities to get every collectible of the game. So make sure you pick all of them up before finishing the game. If you would like to finish the game first and come back afterwards to collect them, it's fine too.
The last act is very short and essentially only consists of the final battle.