Need Real time advice on Yoast Seo

Hi ,
I need advice on setting up the variables for two sections of yoast wordpress seo.
I have read tutorials on the subject and one from the forum itself but when I see the google serps everything is jumbled.
I just need to set up the post types and taxonomies section under Title & Metas with reference to a coupon theme 7.1.4.
What variables should I write in the templates to get the most relevant serps.
Should I use tags as keywords or not. Should I allow categories to be indexed in a coupon site.

Thanks a Lot.

Narender