How to create a good website structure on WordPress?
The first thing you need to do is to take a paper or block note and write your main services and products. If you have too many of them, regroup them under one category. Now look at how many categories you have and how many services you provide. If you have more than 5 of them, you might consider to regroup them under another mother category such as "shop", "legal services", "cooking equipment", "men clothes" and so on. You have to keep your structure simple and easy to navigate.
Additionally, you might consider to use a blog for SEO and content purpose. In this case structure your categories in advance and group your posts by "topic". You might consider to add a side navigation on the right side of your blog.
We use a simple structure for both categories and post on Petra Group website, a local Australian commercial kitchen designer.