There are many ways to improve your ranking in Google using various Search Engine Optimization (SEO) techniques and frankly they can be very effective and has given results. But nothing can beat a good original content which you publish on your site because SEO is changing and 2015 onwards it is all about good content.
What does a good content do for you?
A well written content with a smart title attracts viewers i.e. traffic to your site. Write it in way which helps you connect with your target audience. When people use far too many key words it does get traffic but it will not help you retain the person who is reading your blog for a long time and be assured this will lead to decrements of traffic. Good content is no substitute to key words.
Write the article for the people who want to read it and do not make it very complicated. Use simple relatable language because this is a blog and not some academic paper which you need to submit. What it eventually leads to is your content gets easily indexed in Google.
Any competent agency that has some semblance of knowledge about SEO and ranking can do a more then reasonable job to improve your ranking. But remember one thing there are no short cuts in SEO for organic ranking. What happens is sometimes in order to create a good impression SEO companies end up using Black Hat techniques which are prohibited by Google. When this happens all the ranking is only artificial and the long term ramifications can be catastrophic for your website and business. Also ranking is not static and it changes with location of the search so do not worry too much about it.
Have responsive website it makes SEO easier
Responsive websites are designed and developed in such a way wherein it allows the user to view your website the same way as they would on a laptop or desktop. This is particularly useful from SEO perspective since there is increased User Experience and Google also likes mobile optimization because it brings more traffic and when the content is also of high standard it increases your customer base.