When a organisation decides it needs to improve its Search Engine Placement, there are lots of different paths which may be taken. If a website is decently optimized, it can give free online marketing for that company. It is critical, therefore, for them to decide on a search engine optimization company which will perform their requirements.
If money is no object, then companies can pay for online marketing which makes certain that they always appear on the first page of a related search. They would need to make contact with search engine companies, such as Google and Yahoo! in order to negotiate deals with each one, thereby making sure search engine placement whichever search engine was chosen by the client.
For lots of companies, however, their marketing budgets are limited so the need to ensure they are attaining the best value for money is important. Asking the subsequent questions could be valuable:

What do I want from the SEO Company?
Do I already have an internet site?
Is search engine placement the main concern?
Is conversion to sales the number 1 priority?
Do I want to use a local company?
Is selecting a SEO Company who uses the correct processes important?

If the company does not have a website already, or in-house web designers, perhaps it would be a good idea to talk things through with a company who designs web sites, and includes search engine optimization as part of the package. However if they do have in-house web designers, then perhaps opting for a search engine optimization company who can liaise with their developers to ensure positive outcomes once their web site is finished would be a better option.
For most organisations, web sites will already have been constructed and search engine optimization companies are required to develop traffic to them. Customer briefs will aid SEO companies to attain this, and for this reason it may be important to decide on a search engine optimization company that is located close to your business. They will without doubt want to know if search engine placement, or making sure that your web site appears at the top of the search engine results, is key for the company.
Some SEO firms are paid for optimising the web site; others on a pay per click basis. This will be something to take into account when you make your final selection.
Some SEO companies do not use the correct measures to ensure Search Engine Placement and this can result in your web site being removed from searches all together. Ask the search engine optimization company whether it uses ethical processes to optimize web sites.
Remember, good search engine optimization can provide lots of free Online Marketing for your company, so it is important to choose carefully.