I've noticed that Firefox keeps more spam and bad content out for you, but I do have difficulties looking at some content sent to me by others...
1. Blocked popups (yes, they can be inhibited -- Firefox is your friend! If it wasn't set by default, choose Tools->Options->Content and select "Block Pop-up Windows").
2. Blocking animated-GIF banner ads.
These were once ubiquitous; they're still around, and still annoying. Even if they're not animated, with Firefox you can right-click on any advertisement-image and the menu offers you a choice of "Block images from this server." Block, refresh the page, and you're usually rewarded with a pleasantly blank void containing one small word: "advertisement." Evil sites then refresh the space with an ad from a different server, so you must block again. Continue until your page is ad-free. Truly evil sites host the ads on the same server as their own; when the images you want to see disappear, you must go back, right-click and select "Unblock images from this server." Since so many commercial sites are hip to this, they've taken to creating ads that are just text -- or Flash (see below).
3. Tabbed Browsing.
Until you start using tabs, their utility may not seem obvious. Here's how I use them. Say you're reading a web-page, and you notice an interesting link. Before tabbed browsing, you'd click the link, and thence on to another, possibly losing the trail leading back to where you started. With tabbed browsing, you hold down the "Ctrl" key as you click, and the new page opens in your same browser, but in its own tab, behind the current window, so you can move on to the new site at your leisure. Better yet, if it's a slow-loader, no need to wait -- just go back (or move on) to another tab, letting the slow loading page finish in the background. (With this feature, certain sites' initial non-member commercials can be avoided, like at Salon -- just move to another tab for a while). Note that a tabbed browser is hard to understand until you see it demonstrated. From the mozilla.org page about tabs:
Use tabbed browsing to open multiple Web pages in a single browser window, and quickly flip back and forth. Drag and drop open tabs to keep related pages together.
Some Internauts do something similar by holding down the Shift key when clicking a link, opening it in a whole new browser-window; but I find things much easier to manage while dealing with just one browser. (But if you prefer the multi- window method, Firefox will accommodate you -- see Tools-> Options->Tabbed Browsing. Another quite useful option can be checked there, "Force links that open a new window to open in a new tab.") Sometimes, when I'm surfing furiously, checking the link-heavy blogs I visit daily, my browser may show a couple dozen tabs.
4. Another right-click choice, when viewing a page employing frames, is "This Frame->Show Only This Frame." Kind of esoteric but useful if you frequent a site where you're only interested in that one part (and the rest is static or annoying in some fashion).
5. Now things get technical. Firefox can be customized with utilities called Extensions. (One of these, GreaseMonkey, allows for the execution of Scripts, but that's a whole 'nother ball of wax I won't get into here -- but if you're curious, the one I use most often is the Goggle Image Relinker.) The main extension everybody needs for pleasant browsing is Flashblock. So, what is Flash? Remember in 2) when I mentioned animated GIFs, and how to block them? They was an early method used to make moving pictures on web pages. But now things are more sophisticated, and Flash has become the standard, since Microsoft bundled a Flash Viewer into the IE browser. (YouTube videos are Flash.) What's terribly annoying is if you're still squeezing through a dial-up -- this streaming download can't be aborted unless you disconnect. If you already have Firefox you may have tried to right-click certain annoying animations, and noticed the menu didn't contain a "Block images from this server" option -- somehow, Flash inhibits this. Instead, you must install the Flashblock extension. Since you first need Firefox, however, let's get that onto your machine right now.