If you cannot position yourself as you want in the Google rankings, it can be a problem of content, variations of algorithms or common errors. Many factors can influence your ranking in Google search, from keywords to backlinks. You do not immediately get a good ranking, but you have to work on it and be patient to see results over time. The main algorithms created by Google, for calculating the importance of a site and the ranking position, are changed almost on a daily basis.
Check the Webmaster Tools account to understand what the problem may be and fix it You can get detailed information on your sites visibility and the individual pages that compose it. There are often pages with 404 errors although they do not actually exist and the crawl errors section should be consulted periodically in the site settings to understand where you are going wrong. If you create a site with positive content you will see your rankings go up, while errors and incorrect activities lead to penalties by lowering your rankings. Regarding the problems related to the changes of algorithms, it is difficult to juggle. In fact, it is often difficult to understand what type of penalty or daily algorithm is negatively affecting a website's rank.
The Penguin algorithm of 2012 swept away low-quality sites at a stroke, giving preference to those with higher content and useful to the public and forcing industry experts to re-evaluate their optimisation strategies. The only way to try to avoid a lowering of positioning is to make improvements in setting up the site. If you see that the rank improves, you are heading in the right direction. For example, you may experience better results by including the key words at the beginning of a page title, rather than at the bottom. If over time you see that your competitors are surpassing you, apply new strategies to improve your sites quality in the eyes of Google. Virtually perfect sites are very few and there is always something which can be improved for the better.