If you are looking to really get traffic to your website then you need to think carefully about the keywords you are marketing. When someone makes a search on Google, Bing or Yahoo, the search engines should them results that are best fit for their search. The more generic the phrases the more competition there is for them. For example, if you sold kitchens then the phases “kitchens” or “buy kitchen” would have a huge number of other companies that are trying to get to the top of the search results pages. Instead, you may be better to go for phrases like “fitted modern kitchens” or “kitchen companies in xxx” replacing the xxx with your location. Using more generic keywords but only targeting certain locations can again help you to get better rankings.
If you are using Adwords, the same theory applies. The more competitive a keyword the more money you will need to pay to get towards the top of the sponsored listings.
If you only have a small budget then you are better to invest it into more specific keywords and phrases and target a smaller geographical location. Once you start to achieve good results for these you can then start to expand to cover more search phrases.