I don't know that I can quite answer the first question as I'm not sure what your business is; however, I can answer the second part!
Firstly, the most important aspect in regards to whether someone will open an email or not is "Who is it from?"
If the email is from someone they WANT to hear from ... they'll open it no matter what the subject line is. Think about it. If you get an email from your best friend, you're going to open it. Plain and simple.
The "goal" is to become that person/business people WANT to hear from. And, it's really, really hard to do. It's not impossible ... but, it sure as heck ain't easy ... it's typically done over a long period of time where you're providing value after value after value.
Note: It doesn't have to be over a long period of time ... in some instances, the individual just WANTS to hear from you. For example, my uncle subscribed to a random Bible verse email newsletter. He doesn't know the person sending the newsletter, and he doesn't care to. Yet, he opens every single message because he want's his daily Bible verse ... which in a way, is that value ... it's just much quicker.
Up next you have the subject lines. So, if someone doesn't know you or doesn't really want to hear from you ... you have to "entice" them with an awesome subject line. The gold standards these days with mobile devices is to have your subject line under 49 characters.
So ... in 49 characters or less, you need to convince someone to open your email.
There's literally millions of articles on subject lines, so I won't go into it here. But, if you're having a hard time getting people to open your emails ... spend your time here.
Also, become familiar with split-testing. Nearly all email autoresponder services have split-testing capabilities where you can test different subject lines on different segments to see which performs better.
The next aspect to focus on is the first sentence in your email. Most email clients will show the first 50-100 characters of an email ... basically the first sentence. In this first sentence you need to try your hardest to "hook" the individual so they want to read more!
So, those are two aspects I would focus on right away - subject lines and the first sentence of your email - all the while building a relationship with that individual in an attempt to become "friends."