What should I charge my friend for basic SEO work?

My friend has recently reached out to me asking if I can do SEO for a completely new website of his and asked what I charge. I've looked online but I can only find super professional estimates.

My experience:

• One year professional SEO experience
• No educational experience (I was taught by the company I started in)

What I do currently:

• I do SEO for diverse websites (gays.com and fetish.com)
• I edit a lot of HTML, use Google Ads for keyword researches and use Ahrefs to check on my SEO work

I know im very inexperienced and am a beginner. My friend knows this and we would also run on a trust basis. I am young and have a lot of time to spare after work and am highly interested in earning money on the side to better my quality of life (in Barcelona).

Thanks in advance!