Get backlinks from many authority sites

Hey guys hope you`re doing well, I need few ideas. I`m doing guest posting approx. 6-7 month and get backlinks from many authority sites DA 50+ but I want to improve these two things still and dont know how to do 1. Catchy subject line for better open rate 2. Get many prospect in less time any trick or automation ? Looking forward to your positive response :) Thanks...