I think it looks great!

A decorator friend of mine always suggested grouping similarly colored objects together with lots of breathing space between the groupings. He also suggested using perhaps two groupings on the end of a shelf with a centered grouping on the next.

Thank you! I can't decide if it looks too cluttered? Not enough books?

You have too much stuff on the shelf and it's too balanced - each shelf looks the same with the groups of three look - You need to vary the placement on each shelf. Two items on one shelf, group of three on another, one single large item on a shelf etc.

Layering is part of it also - for example a stack of three books with a glass bowl on top, two pictures overlapping each other etc.

I've posted a couple of shelves which show good accessory placement - use this as a guide.

Thanks for the advice! This is very helpful information!