I think the thing to do is play one first by borrowing one or sitting in on a session, get to know the thing.

Choose carefully ensuring it is solidly built with a good goat skin, try and forget those bloody awful ones with guiness harps etc. all over. The ideal size for beginning would be an 18", gives you a good size skin area to not miss.

Ignore the Bodhran knocking peasants.

Have fun and best of luck