If you’re looking at p0rn on the WWW, then you don’t need to be quite as wary since the material (probably) won’t be stored in an obvious form on the computer for more than a few weeks (unless your browser cache is set to be huge). First make sure you’re not using a public or semipublic machine, because someone may have installed a key logging program, and you don’t want to get caught sticky handed do you?
Also make sure that when you go to a site, don’t just type the address in the Address bar. That may add it to AutoComplete lists (admittedly, these can be flushed, but still) or it may be appended to the dropdown list. To circumvent this, get out a compiler and take advantage of the fact that your browser can load a website as a command line parameter.