A very useful tool that I have grown to love and cannot live without is the Firebug add-on for Firefox. I believe there is also something similar for Chrome but I am not sure if there is anything available that does the same job for other browsers.
Firebug is a free and open source software that allows web developers and of course theme customization freaks like me have an easy day locating all those CSS codes that differs from coders to coders. As there are no standard ruling to govern the use of words when writing CSS selectors, it sometimes gets quite frustrating trying to figure out which part should be changed. Using firebug, you can identify the precise location of whatever you intend to change and it even allows you do do and view the changes in real time.
For those whose Theme has a Custom CSS file like the Neoclassical Theme, identifying the correct id to customize with Firebug is as simple as licking an ice cream. Once you identify the right id and the attributes you want to change, all you have to do is to copy the whole line from the stylesheet, including the hash tag, to your custom css file than add the word, .custom in front. Then you can change whatever values you like inside those curly brackets.
Not only can you use it to do your own customizations, you can also use Firebug to check out other sites that you fancy so you have an idea how to create something similar. I will let this video from Lisa over at How To Create A Website tell you more about using Firebug.
Firebug is an excellent tool, although sometimes you might see “errors” that u can’t really see on the page and/or are not important at all.
There’s also another Firefox plug-in using Firebug, which is called Page Speed. I will tell you what you can minify on your blog to achieve higher loading speed.
It will report for uncompressed images, css, js etc. I spent some 3-4 days few months ago on optimizing my blog with those addons and I was pretty satisfied with the end results
Too have installed the page speed addon but never really got down to using it. LOL.