From the default Firefox install these are the settings i change to make my browsing life that little bit easier and safer.
Type the web address you would like as your homepage into the address bar (or use File > Open Location.../Open File...) eg. www.google.com and hit enter so it displays the google website. Now go to Edit >> Preferences.
In the 'Home Page' section click the 'Use Current Pages' button as we allready have our homepage displayed in the browser window.
Leave the 'Preferences window open and continue below.
The defualt settings in general are fine, it's preferential if you want Firefox to check for updates on startup, personally i choose not to do this.
I change this to 3 days instaed of the defualt 9, adjust to taste.
I prefer to keep all private information private, so unticking the 'Save information i enter in web page forms and the Search Bar' makes me feel a lot happier.
Same deal again, untick to not save passwords.
Change this to 'When Firefox exits' or 'Upon succesful downlaod'.
I leave the option to 'Allow sites to set cookies' as it can hamper browsing to remove it, but change the 'Keep Cookies' setting to 'Until i close Firefox'.
Left as default.
I find the default settings fine but use the 'Advanced' button next to 'Enable Javascript' and untick:
Move or resize existing windows.
Raise or lower windows.
Disable or replace context menus.
Change images.
'Hide the status bar' and 'Change the status bar text' shoule be unticked by default.
Personally i like to to be asked each time i download a file so i put a tick into 'Ask me where to save every file'.
I find the download window just gets in the way so i untick 'Show Download Manger windwo when a download begins'.
Left as default.
Put a tick into 'Begin finding when you begin typing', this comes in very handy as there is no need to use Ctrl + F ( or Edit >> Find in this page) to start a search on the current page.
Untick 'Resize large images to fit in the browser window'. As i find i get a distorted image (mentally) of an images size using this option.
Change to 'a new tab in the most recent window'.
The remainder can be left on their default settings, so click the 'Ok' button.
Back in the browser go to 'View >> Toolbars' and untick 'Bookmarks Toolbar' to reclaim a little screen real-estate.
Next go to 'Tools >> Extensions' and click on 'Get more extensions'. This will take you to the mozilla extensions page for Firefox.
There are a lot of handy extensions that enhance and compliment Firefox's functionality, some of my favourites are:
'Advanced Eyedropper, Color Picker, Page Zoomer and other colourful goodies'.
'View and manage downloads from a tidy statusbar'.
'Performance and network tweaks for Firefox'.
'Takes a screen shot using Java'.
'Magically restores your last browsing session'.
'Enhances control over some aspects of tabbed browsing'.
'Assign tab related actions to clicking events on a tab or the tabbar'.
'Adds a menu and a toolbar with various web developer tools'.