Dr. Dave Hone has put up a great little post about palaeo-art on the Guardians website. It also includes the art of long time ART Evolved friend Matt van Rooijen. While I suggest reading the whole thing, I grabbed a small snippet that I thought was of particular relevance to people on this site.
Dave Hone discussing his take on how people can get into palaeo-art. A very honest, and I think accurate assessment.
As for how people get into the field, well this naturally varies. I know of artists who were working as technical illustrators for scientists and were in a position to have a go at the odd life reconstruction and things went from there, there have been wildlife illustrators who were drafted in because they could do animals properly, "normal" artists who found a flair for it or drove themselves into the field, and those who simply got a call out of the blue and asked if they fancied trying their hand at dinosaurs.
Increasingly though, thanks to the internet we're seeing ever more people being able to gather information on palaeoart and prehistoric animals, get feedback from researchers and push their art in front of those who might pay for it. Where even 10 years ago it was probably hard to get anyone outside of the ranks of publishers and researchers to have heard of you, or seen what you can do, it's becoming ever easier to mail prospective clients and send them a link to your online portfolio and have people share that information.
This is great for those wanting to break into the field, but naturally it has brought tension too. Most researchers have enough on their plates without having to deal with detailed requests for help on tyrannosaur or abelisaur anatomy and while I know of few researchers who would turn such a request down flat, one does occasionally get most unreasonable requests. Moreover, there are now dozens, perhaps hundreds, of budding artists working out their dinosaurs and mammoths and trilobites online and offering their services to researchers and museums just for the chance to have something of theirs used.