Unfortunately I see this all the time, and most are solvable with small tweaks that make a HUGE difference.
 
Mistake 1: Being too boring & formal
 
Remember that people usually read emails on their “dead” time, the last thing they want is to read a boring email with just plan information.
If they wanted that they would go to blogs or YouTube.
If you can’t be entertaining your readers it will be hard to maintain your reader’s attention throughout every email thus making selling a struggle.
 
Mistake 2: Not igniting curiosity
 
The goal of your email is to make your reader follow-through with the call-to-action, and if your emails are not igniting his curiosity no one will want to click on your link.
One of the best ways to do it is by praising what’s inside the link you’re sharing (could be a course, blog post, tweet, etc…) without ever dropping the ball and revealing what it is.
You can even go as far as saying that X, Y, Z people do/know this (what's inside the link.)
 
Mistake 3: Forget to build a relationship
 
Email is ALL about relationship building, and the better you can create an ecosystem of your own, the easier it will be to get your readers to trust you, vouch for your work, and buy the offers you promote.
You must be brutally honest and have your reader’s best interest in mind.
You must commit to being there and to mutually help your readers.
You must share about yourself.
 
Mistake 4: Forget that you're the authority
 
It’s your list, you own it and you’re the authority.
If you want people to believe in you, then you must fully believe in yourself and properly transfer your certainty about what you’re saying and what you’re selling to your readers.
 
Mistake 5: Forget to build the list
 
This one is self-explanatory, but if you want to do email on the long-term, you MUST never forget that you need to keep on putting efforts to grow your list.