A BIG +1 for smoke detectors.
Minimum - one on each level of your house.
Better - One on each level, interconnected (one detects smoke and alerts, they all go off)
Best - One in each sleeping area / bedroom, then one on each other level as well, all interconnected.
Roll up ladders are good as "last ditch" items - I've never used them, but I'd stick to a known brand like First Alert or Kidde, rather than the chinese generics on ebait.
And practice. Make sure everybody knows:
what the smoke alarm sounds like
what to do when it goes off (feel door for heat; make GO/NOGO decision; stay in place or alternate exit strategy)
How to exit - crawl under smoke, in the dark, etc.
where to meet once you're out.
And DO NOT GO BACK IN.
Remember the phrase "you fight like you train"? Well, you survive like you train as well.
If you've got little kids (baby/toddler) pre plan who's gonna go for which kid. Talk about 2nd means out if you're trapped in their room, and means of evac if needed. Do it now while it's still "what if" rather than when it turns into "WHAT NOW".