A common mistake that webmasters often make is they underestimate themselves. Do not underestimate yourself. Even if you are number 10 in SERPS or number 100. Things can always pick up. Remember that SEO takes time.
Another thing not to do is believe everything you see on the internet. You can use as many search terms as you want to look for SEO strategies but different things works for different people. Of course there are the basic SEO tricks that work for everyone, just basic SEO, but other things that people try with their websites that work for them may not work for you. So keep trying things with your website until you find something that works for you.
Just because you find something that works for you, do not be stupid and cancel out all other techniques. You will exhaust your current one eventually.
The number thing to avoid when it comes to SEO is: Avoid all black hat methods! Sure, you will see short term benefits but it will cost you a lifetime ban. It's not worth it.