How to avoid the mess?

I tend to pile stuffs on my slides and it can sometimes make it difficult to maintain them.

I end up with zooms and text and shapes and pictures overlapping, usually for good reasons but it is often difficult to select the right object.

I try to use the lock feature to avoid clicking on the zooms once they are set. Also I keep hiding and unhiding shapes... but there must be a better way!?

Using layers is an option of course but it makes the visualisation of the timeline quite difficult. Especially if someone else has to do the maintenance.

What are you tips?