Hootsuite This is a platform to schedule multiple posts in advance and see how all your social media activity performs in one place. Free for up to three social media accounts.
Canva With Canva you can create easily create posters and templates to promote your business in different channels.
Later This is a really useful blog that talks about everything from trends, to posting times, to types of post. They also talk about the latest (seemingly weekly) changed to the algorithms. It’s useful for anyone getting started with Instagram.