The reason that a number of webmasters prefer to do their own SEO is because they can no longer trust anyone to do SEO for them because of the risks involved. Search engine optimization is very important for the improvement of rankings and there is no doubt about it, but you have to be careful with what you do as certain backlink types are known to cause a negative effect on your rankings which you should definitely be knowing about.
The problem with SEO is that, no one can tell you exactly what factors can help you get the much desired number 1 ranking. You have to be building a wide variety of backlinks to see an improvement in your rankings in terms of seeing an upward movement for each one of your keywords.
When choosing a service provider for the improvement of your keyword ranking positions, make sure you choose a company that has existed for a while because such a company would have gone through all of the search engine updates that were implemented over the years knowing exactly what precautions to take for survival.
A new SEO provider may not be aware of all these challenges as they may just be on their experimental phases. You may also want to do your own SEO and outsource only the tedious part to SEO companies. If you get tools like seo rank checker, then things could become a lot easier for you.