The central point to get the most recent personality library is http://personalities.avolites.com/ - this library is frequently updated. Here you can also request new personalities, and can browse the library. More often than not you'll find that a certain fixture already exists under another name, by another brand. In order to update your personalities, download the package for your console, run it on the console - which will copy all the files to their correct folders - and restart Titan. That's all.
Another source of knowledge is the personality section of the forum. Here you get advice about particular details regarding personalities - and if it is niclights who answers then you better listen carefully: he is the one who creates most of the personalities today.
Another interesting thing is the Advanced Personality Search: this allows to search for fixtures with a particular channel layout, e.g. for fixtures 'with 19 channels, 1=Pan, 6=Dimmer, 8=Red, 11=White' Search and result might look like this: