First and foremost, Google analytics is absolutely crucial in driving quality traffic. The ultimate mistake in driving traffic is not tracking your results. Google Analytics allows you to track conversions (goals), tells you which traffic sources are converting the best, and lets you segment your data so that you can go out and find more high-quality traffic.
After tracking, you need to make sure you’re doing your market research. If you don’t know anything about your demographic or target customer, you’re going to end up driving untargeted, low-quality traffic to your site that doesn’t convert. Quantcast gives you a demographic profile of your site, or, if you’re too small, your closest competitor – so you can get a feel of what audience you should be targeting.
Another tool in optimizing websites – Clicktale and Crazyegg give you in-depth information on how your visitors behave when they get to your website.
Crazyegg offers heat map tracking – showing you what places your visitors click on the most. It can show you places where you should have something for sale – for example, you might have an image that gets a lot of clicks – maybe that means you should link that image to something.
Clicktale goes a little more in-depth, offering actual recorded sessions of how your visitors interacted with your page.
Google Webmaster Tools basically gives you an in-depth look into how your website is functioning. It shows you what your page load time is (according to Google), which is a known ranking factor, it shows places on your site where there are errors or broken links, and it shows you your impressions/clickthrough rate/positioning for keywords.
Ahrefs is a tool I recommend all internet marketers and bloggers use. It pays for itself.
You can find out all about a site’s search engine optimization. I’m talking, backlinks, social media shares, all the keywords it ranks for, 404 pages, broken links and much more. This tool will show you where you are going wrong with your SEO and how to fix it.