You can ask the service providers to show you the reporting structure and format before you hire them. Make sure that the SEO agency shares weekly or monthly reports and analysis for your site so that you can keep a track of the progress of your project. Cost is an essential factor that you should take into account while hiring an SEO company. You can get multiple quotes and compare them too. A lot of service providers offer free, no obligation quotes to the customers. Collect as many quotes as possible and choose to hire reliable and expert SEO agency.