Here's the chronological order of events in all Dead Space media, from my memory and this timeline on the Dead Space wiki.
- Dead Space: Martyr (novel, 2010)
- Dead Space: Catalyst (novel, 2012)
- Dead Space (comics, 2008)
- Dead Space: Downfall (film, 2008; takes place at the same time as Extraction)
- Dead Space: Extraction (game and comics, 2009)
- Dead Space (game, 2008)
- Dead Space: Salvage (comics, 2010)
- Dead Space: Aftermath (film, 2011)
- Dead Space (mobile game, 2011)
- Dead Space: Ignition (game, 2011)
- Dead Space 2 (game, 2011)
- Dead Space 2: Severed (DLC, 2011; takes place at the same time as Dead Space 2)
- Dead Space: Liberation (comics, 2013)
- Dead Space 3 (game, 2013)
- Dead Space 3: Awakened (DLC, 2013)
In my opinion, either play/read/watch it all in chronological order, or by date of publication, which I've put in parentheses after each work. Order of publication is usually the way to go for most media, as that is how the creators "meant" them to be presented to you.
There are some plot points that are "spoiled" if you go the chronological route, but that mostly happens if you read works set prior to the events of Dead Space (the main game) before playing it, but since you have played it already I'd say you can go either way.