My blocking extensions:
Adblock Plus, Beef Taco, BetterPrivacy, Clear Private Data (puts the clear-data control under the right mouse button), Element Hiding Helper for Adblock Plus, Sanitisminau (correct spelling) and last but not least, arguably one of the most important, in fact, PrefBar.
I discovered PrefBar (Preferences Bar) way back when Firefox was still Netscape. It puts a bunch of controls across the top of the browser, some of the more important being Cookies, Popups, Send Referrer (great!!), JavaScript, Java, Flash and more that I don't use.
As well, I use Mozilla's about:config controls not only to help prevent tracking but to stop the address bar's propensity of making public sites I've been to, searches I've made, "helpful hints" if I typo an address, prefetching that plants tracking cookies from sites you never visit, pings that augment prefetching. . . .
Type about:config in the address bar and you'll see what comes up. Click OK at the warning. There's nothing dangerous if you don't change the text, which takes a lot of doing.
But to make my about:config changes remain through application updates, I made a
plain-text document called user.js that modifies the prefs.js file that controls about:config. This user.js file goes into Firefox's Profiles folder, where prefs.js and all the other stuff, such as bookmarks, resides.
mozillazine.org has tons of stuff on all this, but it is not affiliated with Mozilla (and at the moment appears to be down). But its forums are operating.
When it's back up I'll find the page with all the about:config modifications and their explanations and post it in this thread, if you want.
Among my browser modifications:
user_pref("browser.urlbar.maxRichResults", 0);
user_pref("places.frecency.unvisitedBookmarkBonus", 0);
user_pref("places.frecency.bookmarkVisitBonus", 0);
user_pref("places.frecency.unvisitedTypedBonus", 2);
user_pref("browser.urlbar.matchBehavior", 2);
user_pref("browser.urlbar.matchOnlyTyped", false);
user_pref("browser.chrome.favicons", false);
user_pref("browser.chrome.site_icons", false);
user_pref("browser.blink_allowed", false);
user_pref("accessibility.warn_on_browsewithcaret", true);
user_pref("browser.send_pings", false);
user_pref("network.prefetch-next", false);
user_pref("browser.send_pings.max_per_link", 0);
user_pref("browser.send_pings.require_same_host", false);
user_pref("extensions.bprivacy.sendpings.allowed", false);
user_pref("dom.storage.enabled", false);
user_pref("app.update.auto", false);
user_pref("app.update.autoUpdateEnabled", false);
user_pref("app.update.enabled", false);
user_pref("browser.history.showSessions", false);
user_pref("browser.history_expire_days",0);
user_pref("browser.history_expire_days.mirror", 0);
user_pref("browser.history_expire_days_min", 0);
user_pref("browser.sessionhistory.max_entries", 0);
user_pref("privacy.clearOnShutdown.history", true);
user_pref("privacy.cpd.history", true);
user_pref("network.http.sendSecureXSiteReferrer", false);
user_pref("keyword.enabled", false);
user_pref("geo.enabled", false);