Here are some of the tools I use and recommend.
Note: Some of these links are affiliate links and I may earn a small commission but I don't recommend anything that I don't use or love myself
I love Kajabi because it houses my website, courses and email marketing in one place. When I was looking at it, I thought it was expensive (I pay around £130 per month) but because I was paying for web hosting and an email list separately, plus having somewhere to host my courses, it wasn't much different in the end. It's easy to use and there are no extra costs (email subscribers are unlimited).
Perfect for tracking your time on projects and knowing how long things take you to deliver a project or retainer. The free version is fine, but I use the paid version to give me billable vs non billable amounts.
I love Smarterqueue for posting to social media - I can set it up for the week and then just leave it to happen. For Instagram it just allows you to copy but then it looks like you have posted directly.
As an accountant I use Xero all the time, and I cannot recommend highly enough that you have an accounting system. I can set you up with this and the software is usually around £28 per month. You can send invoices, reconcile payments and generally get on top of your accounts.
This is a great tool to prevent you going backwards and forwards with people to book a time to chat. The paid version of Calendly (around £12 per month) allows you to take payments, so this is great for paid power hours (pick your brains chats!).