How do i go about using SEO for my site?

Hey so i set up my site about 2-3months ago and i have a lot of helpful content on it its mainly just ad-sense, but i have a few affiliates on there. I have managed to work my way up and am on average of about £0.50 - £1 a day and have made 2 sales giving commition of £110 in all i get around 50-100 visitors a day from organic search the site relys a lot on search traffic i have around 100 articles that i have written and a lot more to come i make about 1 a day but i am having trouble with how i should SEO this site, i really need the site to have a high Domain Authority i guess due to the fact that i cant really hardcore blacklink every post i do but i am just not sure on how to go about doing this i dont think PA will work at all for this site but i am new so i could be wrong.

Thanks a lot if i have missed some needed information please ask.

P.S. i am really new to this so please don't bash me we all have to start somewhere :)