Yes, there is a strategy to using hashtags on social media platforms. Use hashtags sparingly and only when they add value and meaning to the words in your post. Overdoing it with how many words you hashtag in a single post, or how many words you put into the one hashtag can be confusing, ugly, and quite truthfully annoying.
Using more and more social media platforms does not necessarily mean more success with online presence and branding. The same holds true with having too many profiles/pages. In fact, it can very well be counterproductive and cannibalise online activity and credibility. Much better to choose only a few, use them regularly, and use them well!
There is no magic trick to SEO. To achieve good (high) search engine rankings, you need to take an all-encompassing, ground-up approach, and implement an SEO strategy that is closely integrated with the making of your website. A site rich in content but also a design with strong User Experience.
Obsessing with your website's search engine rankings is not healthy; for you or your website. Play it cool with SEO and results will come!