Everyone who has been doing web development long enough knows that notepad and macromedia dreamweaver are probably the favorites for beginners but yet not enough to meet your needs in more advance levels.
For those who are seeking, IBM had written 2 related tutorials on using tools such as Firebug, Web Developer exension and GreaseMonkey, which are all famous and ecommended tools these days.
Upgrading your toolsets (especially with those mentioned above) can mean a lot of things. With a little bit of learning curve and spending some quality time learning, I believe it can definately help increase your development process and shorten your development time in the future once you have master them.
Article 2: Debug and tune applications on the fly with Firebug
* I learnt something new today about Profiling after reading this, even though I had Firebug for more than a year! *