For 'scene' releases, use a public predb such as
orlydb to search for release names. Plug the release name into
binsearch.info, if it's something even reasonably popular it will have been uploaded at least once. Select what you want to download, hit 'Create NZB' and Bob's your uncle. You don't need someone else to create your NZBs for you!
Once you start doing this often, you'll find a few hacks:
a) Start using Google Chrome as your web browser if you're not already; set up search engine keywords for orlydb and binsearch. Saves massive, massive amounts of time
b) Use the SSL encrypted version of binsearch.info; if you want to plausibly deny what you're downloading from usenet it's pointless not having your search and download of NZB files encrypted as well
c) For the love of all that's good start using SABnzbd+ and forget about messing about with par2, rar, etc. files manually
d) Find an application (On OS X there's
Hazel) that automatically takes .nzb files from your downloads folder and places them in a designated folder that SABnzbd+ monitors. As soon as you download an NZB, it'll get added to the SABnzbd+ queue, it'll be downloaded, parity checked (if applicable), unpacked (if applicable) and ready for your perusal without you having to lift a finger
Happy usenet-ing!