I know a few people have suggested mixed reviews on guest blog posts. Here is may take on it
In the past (pre 2012) guest blog posts were a fantastic way of easily ranking for keywords however since then they have been devalued massively.
In the modern day, they still have their place but you have to be bringing something to that website and its users. If you have a football tips website (ive not looked at your site) then you could write on websites that already have an established base looking for people to write extra articles. There are many available. You would need to be offering them free tips or thoughts on actual modern day things. Keep the users engaged. This will not only help your SEO but you will get some natural clicks via that website and their social media following.