I would take
Sailors on the Starless Sea as a good model.....lots of ways to die; lots of ways to avoid death; a couple of chances to gain new funnel characters.
The more chances there are for players to think their way through things, rather than to simply roll, the better the chances that PCs will survive. Of course, you don't want
all of the PCs to survive, so you need to include some combat encounters and some places where the PCs have enough rope to hang themselves.
I would recommend starting with a situation, writing out all of the encounters, and then going back and putting statistics to what you've written. Consider that, against a creature with a +0 to hit, the average 0-lvl PC is going to go down in a little less than 50% of the hits, because few PCs have enough to stand a second hit. But, where there is a single monster and a gang of PCs, that gang has an advantage. Consider giving the PCs a chance to replenish their numbers after "gang" attacks, but not after single monster attacks (no matter how brutal)....again, what you see in
Sailors.
I would also consider picking up every funnel you can for design ideas. I've run
Perils of the Sunken City,
Attack of the Frawgs, and am halfway through
Ooze Pits of Jonas Gralk. Each is different. Each has very real dangers. Each has a good chance of killing off a few 0-level PCs while letting a few others go on to 1st level.
Remember those 1st level D&D and AD&D modules back in the day? They didn't worry too much about how the PCs were going to survive. They set up situations where the PCs
could survive, but if the players were insistent on fighting the minotaur in the Caves of Chaos, well, that wasn't the DM's fault. I've run
Portal Under the Stars where the PCs suffered minimal casualties through good play, and I've played where no one got past Area 3. I give the players the credit in all cases. If one adventure seems easy, well, there is another one coming up that might seem hard.
Finally, look to
Sailors to see how several encounter areas build up the party so that they have a better chance to deal with what comes thereafter....often in knowledge, but sometimes in items that give them an edge over upcoming foes. Not everything has to be a fight, and sometimes a period without a fight makes the upcoming bloodbath all the more visceral.
The post linked to above is a good one; you should read it.
See also here:
http://ravencrowking.blogspot.ca/2012/0 ... ngeon.htmlGood luck!