Hey kctynan, welcome to drumdojo.
A lot depends on where the people are whom you wish to protect from the sound of your drums.
If there is a physical connection (such as floor/ceiling joists or party walls) between the room that you are in and the space of those whom you don't wish to annoy or you are in shared accommodation then ouch!
If other people are in a physically attached space then there's going to be no easy way to completely isolate the sound of your drums unless you float a
room within a room which is both costly and complicated -
Chris Whealy's blog covers this process and many of the issues in quite some detail.
There are some measures you can take to reduce the impact but your fellow residents will still be able to hear you.
High Frequencies - use carpet on the walls, line it with mattresses - also have a look at the
article on using Mass Loaded Vinyl to see if that's any use
low frequencies - build a floating drumriser/ floor on top of the existing floor, I've heard of people using boards on top of car tyres for this but I've not done it and can't vouch for its effectiveness.
I have also seen commercial standalone RWAR solutions but they are heavy and expensive.
Most of us have struggled with this for years, usually working around it by identifying periods of least annoyance. I've never had the pleasure of being able to set up any more than 30ft from a neighbour's property nor having my own independent space, a dream!
I suggest you have a read at Chris' blog and see which bits can apply to you. He's certainly very approachable if you felt there were specific things that he could help you with
Sorry I'm not much more help but I wish you well with the quest.
Paul