What to get paid for SEO

Hello! I've been doing convent writing for the last 3-4 months for a company blog where I would receive a prompt/keyword and ghost write an article. Since this was my first time doing work like this, I just went off the pay rate from their last writer of 8 years which was 15¢ a word. I would write and format the blog posts and do some on-page seo through semrush. Now that I have more experience, I want to start doing more of the process, including keyword research, content writing, on and off page SEO, and start working on backlink building. My employer is totally on board, because he runs the business himself and doesn't have the time to focus on the SEO aspect of it. My question is how / what do I charge for this type of work? We're going to have a meeting soon to discuss my job becoming more autonomous and I want to have some sort of idea what to ask for when pay comes up. So far the amount of work has been inconsistent, because I have to wait on prompts at this point so I'm hoping to create a steadier stream of income with this. Thank you so much!