carpet the floor if you can. Soften everything in the room with pillows, mattresses, anything soft. Take away anything that is glass, hard stuff. Break the room into 'waves', use auralex foam if you have lots of money, if not, stack up books, use bookshelves, etc.
Clap your hands, if you hear an echo, then dampen your room some more.
Avoid over deadening your room (eg. overuse of auralex), if not your recording will sound rather 'dead'.
If you really have loads of money, auralex every wall, ceiling, use bass traps, etc. a few thousand bucks here.
If not, use houshold items like blankets, pillows, mattresses. Ugly looking but does a decent job if you do it properly.