I kinda do, that's why I try out stuff from time to time but with marketing it's so much harder to measure success and you never know if something does not work

I kinda do, that's why I try out stuff from time to time but with marketing it's so much harder to measure success and you never know if something does not work because you're doing it wrong or because it just does not work. Example: I wrote a lot of journalists that published articles about education-software if they want to review our app, no responses. The mails were personal, not templates. Did I wrote to the wrong persons or were my mails not good or do they not care? Or something completely different? Then I looked up blogs, sponsored posts but our traffic did not change so much. Did I write to the wrong blogs? Are the users not the target group? How to measure and learn? I'm not so good with social media like facebook or twitter, I don't care enough and I don't want to share too much personal details, but now I try to work on social media marketing. Maybe that's what our app needs, again how can I measure success and how can improve if it does not work from the beginning? For me that is a black box...