If you have a web agency that has designed and built your website or even just taken over the management of it then it is advisable that you work closely with them. You may give them a certain amount of money each month for them to invest into different marketing avenues on your behalf or you may give them work on a project by project basis. Whichever way you work with them you need to ensure that you spend an adequate amount of time working alongside them to get the most out of your budget. Some of the work they undertake may require limited or no input from you, whereas other work may be more affective if you can get involved. For example, if they are writing content to go on to your site or on to other sites to get a link back to yours then this content should have your input after all its your business. The best way to do this would be for you to write out the article and then for them to add in the elements that are needed to SEO. Doing it this way will also mean that they can spread your budget further than if they were having to do research and then write it all from scratch.