Use the General sub categories, this category will probably expand as time goes on to cater for more non specifics.

A place for Vendors to post any products / promotions / giveaways.

This category is all about e-liquids if you want to specify we have the Mixology Category

Use the sub categories to discuss anything related to vape hardware.

Reviews will be split up into their respective sub-categories for better accessibility.
You could use [REVIEW] at the start of your title if you want.

For the discussion of anything to do with mixing your own E-Liquids, please use the provided sub-categories, thanks.