Google does not use Meta keyword but there may be other services and sites that use keyword tag to get idea about your content. There is no harm to use Meta keyword tag. But if you are focus only on Google then avoid using keyword tag.
Videos submission helps in getting more traffic to your website, it helps in building more back-links for your site and the good thing is one video can be submitted to several sites.
Content of your website is very important for long term result. First you should focus on quality and fresh content. Do on-page optimizations like website design, Meta tags, image optimization, keyword research, robots.txt, and search engine friendly URLs etc. Create high quality back-link by...
Make a board under your company profile where you can share your images. we can alter the source url when making the pin which gives additional traffic to our website. No doubt social media sharing is also an important factor of seo.
If you new in SEO then I suggest you to read articles on reputed blogs or SEO resources like MOZ, "Search Engine Land", "Quick Sprout" etc. Read SEO Glossary on "MOZ" and try to understand each term. If you are already familiar with SEO then try to buy good paid books for SEO.