Disable Javascript. Enabling it makes you traceable. Run a Temporary profile in Firefox - otherwise cached images will make you traceable. Connect from your neighbors wifi (the further from your home the better, really) with a spoofed MAC address running from a write-locked USB live distro - this ensures you're protected from the unknown unknowns.
Or just use the Tor Browser - ideally with the High security setting. Other browsers don't have the same anti fingerprinting and first party isolation defenses.
