I'm DMing a group with 4 players. For all of us, this is our first D&D experience. We'll be playing the Lost Mine of Phandelver adventure from the Starter Set.
I'm concerned about the survivability, especially given how green the players are. At first level, they'll have 10 or 12 hit points, facing groups of goblins that can hit for 1d6+2. I'm adjusting the number of monsters in each encounter, but still worry.
Healing seems to be very rare. At first level, the spellcasters will have the ability to cast two spells in an entire dungeon.
The Epic Heroism resting variant (DMG, p. 267) seems like it could help, but might tip the balance too far the other way into easy mode:
This variant uses a short rest of 5 minutes and a long rest of 1 hour. This change makes combat more routine, since characters can easily recover from every battle. You might want to make combat encounters more difficult to compensate.
Spellcasters using this system can afford to burn through spell slots quickly, especially at higher levels. Consider allowing spellcasters to restore expended spell slots equal to only half their maximum spell slots (rounded down) at the end of a long rest, and to limit spell slots restored to 5th level or lower. Only a full 8-hour rest will allow a spellcaster to restore all spell slots and to regain spell slots of 6th level or higher.
Am I missing some element that would make the party more likely to survive the first dungeon, or would this rule variant be a good way to introduce the mechanics of the game?