One of the most important elements of an effective Google Adwords campaign is selecting the right combination of keywords and keyphrases. There could be millions of keywords associated with your niche and playing a guessing game for the 'right' keywords can be costly. Google offers its own keyword selector tool to make the process of choosing keywords easier, but there's are a handful of other tools you can use to fine-tune your campaign.

Adwords experts follow a three-step method for keyword and keyphrase building. The first step is to use the most common and obvious terms and run them on a keyword tool to find out each keyword's search volume. The second step involves finding out relevant keywords and other appropriate terms being searched by your target markets. The last step focuses on optimizing a campaign by tweaking or removing keywords for better results.

The three-step method described above cannot be implemented without a reliable keyword tool. Howie Jacobson, author of 'Adwords for Dummies' gives out the four most reliable keyword tools that you can use for your campaigns: Google Keyword Selector Tool, Keyword Discovery, Word Tracker and a plain Thesaurus.

The most popular tool is Google's Keyword Selector Tool. It is free and you can access it through your Adwords account. The tool allows you to run your keywords on its system and provide you with synonyms or other relevant keywords in your niche. This tool can also compare keywords based on a wide set of statistical data such as search conducted per month, average searches in a year, average cost per click and many others.

Keyword Discovery is a paid service that allows you to manage several lists of keywords, compare data, and produce reports with ease. This is a more robust keyword analysis tool than the free Google Keyword Selector Tool, and is most appropriate for experienced Adwords users and SEO experts. If you're comfortable with paying for the service, Keyword Discovery can help you create comprehensive lists of keywords to help you target very specific groups in your market.

Word Tracker offers both a paid service and a free tool for analyzing keywords. The free keyword tool provides very basic information ,namely, the number of searchers conducted for your keyterm within the month. It's a quick an easy to cross reference search volume for a particular keyword, but the numbers may not be as accurate as the Google Keyword Selector Tool.

Keyword tools are really effective at digging deep into a niche and getting long-tail keywords and other relevant keyterms. Keyword tools are convenient for comparing hundreds of keyword data side by side and even allow you to export all your work into an electronic spreadsheet or other soft document format to back-up and store your data locally.

Understanding what your target market is searching for will help you create compelling and high-impact Adwords ads which in turn can increase click-through rates. If you're just starting out, take advantage of the free tools available and print out or organize the results to build your baseline keyword list.