The improvement in terms of performance for a website has a lot to do with the kind of SEO that was implemented in it. They happen to know a lot about SEO. They know a lot about what is happening in their industry, and come well prepared for internet marketing. There is rarely a shortage of consultants when you wish to have their services. You only need to know what it is you need from them.
You need to take time to read the kind of personality they have. You cannot trust those who keep on blowing their trumpets too much. You need someone whose comments are based on reasonable facts. Give a chance to those who seem reasonable both in expression and in analyzing situations. That type never fails to disappoint in the end.
You need one who is well informed. You need to find out some few things about SEO, so that you can keep up with their communication. This greatly helps in determining whether they are good for it or not. You need one who will not be challenged by new things in their line of work. Those who are not so well informed will not do a job.
You need one who will bring your website to the forefront of the development frontier. It is best to work with those who will install the latest SEO features on your website. You also need to have one who will make sure there is a good rapport between you. They need to share their ideas, and consult before implementing any. This way, you get to offer your opinion and input as needed. At the end of the day, the site is yours. You get to decide how most things end up anyway.
You also must have a look at their portfolio. This is an important step. This should be readily available for your viewing. You need to see proof that they deliver on their promises. This is good for your business, as you have approached them looking for results.
You then need to do a comparison of what they are asking for and what they are giving. You will come across some who are charging wither too high or too low. Avoid dealing with those. You should expect reasonable prices for reasonable demands. The end result should be excellent. Your business should then receive positive results from their efforts, which will go towards increasing the profitability of the business.