People always talks about SEO, should one do it yourself or hire an agency? You can do SEO by yourself as it is not a rocket science, but optimizing website for users DIY is not possible for everyone. You have to hire SEO agency to make your website good for visitors as well as search engines. I know Google always tells that make your website better for real users not for bots. If a website is good for visitors, real users then by default it will be good for search engines also. Google always keeps changing its algorithms to make search results better and keeps websites on top which are really good for human visitors. SEO is must either you do by your own or hire an agency, but expecting top ranking by SEO is not good. No one can guarantee top ranking, but there are agencies which can optimize your website for better visibility. What do you think?
If you knows seo(on-page, off-page) better then you can do it by yourself. And on other hand hiring seo agency is much better than this because they always update themselves by recent google updates and also have knowledge of html. So its good to hire seo agency.
SEO agency are more updated in SEO. they have responsibility for promoting the website in google. There are lot of technical person are available in agency who doing SEO in proper way. so i suggest you contact to SEO agency.
If you know good SEO you can do it yourself. But if you are a newbie and experimenting with things, you might get something wrong in the very beginning if you are up to something serious, e.g using some typical black hat methods that freshies usually do. So its better to learn SEO properly in the first place and hire some consultant or agency to help you out completely or partially with the SEO work as well.
As you are providing SEO services (your signature shows that), you should hope that people will hire an agency to rank their websites. From my point of view, if you are talking about a site within a lot of medium or high competitive market, you should hire an agency in that case. While you are talking about site in a smaller market with low competition, you can do it yourself. Still the choice is yours.
I think hire a company for SEO work is the best option because in a SEO company your website can get the perfect way from the SEO Experts. So it will helpful your website to get more traffic and get better result in Search Engine.