Rehabilitating an old Fountain Pen

Wow, I didn't realize there were folks really into pens...that's great!

Anway, here's my question. What's the best way to get a fountain pen you haven't used in a while "flowing" again? Mine still has the old cartridge in it and I think it may be a little gunked up :-(

Should I just soak the nib in warm water or something?

Also - what's the best way to store the pen if it isn't used for a while?

Thanks!