The biggest problem I have with surprise is when to start the encounter.
The encounter doesn't start with the first attack roll, it starts with Stealth vs Perception. However, if a stealthy party doesn't notice the other party until too late, the opportunity for stealth vanishes. Also, there are issues about how far ahead to send the scout, etc.
So let's make this easy. We're in a dungeon, so the ranges are very limited. There are four PCs (a rogue, a wizard, a cleric and a fighter) walking down a hallway, coming to a T-shaped intersection. The rogue creeps up ahead, looking around the corner to see if anything's there, while the rest of the party waits silently.
He sees a party of orcs who aren't trying to use stealth. He makes a Stealth check, opposed by the
passive Perception of the orcs. (The orcs aren't using active Perception because they aren't looking for anything.)
This is a good time to roll initiative for everyone (even though probably only the rogue will go in the surprise round).
The rogue could summon the rest of the party, but they're not stealthy and will make noise, plus they're not that far behind, so he pulls out his light crossbow and shoots an orc. The orcs didn't make their Perception checks and are surprised. He gets combat advantage against the orc, and so gets +2 to hit (and sneak attack).
First round of combat commences. The rogue (having the highest initiative) probably goes first. The orcs are
not surprised and the flat-footed condition from 3.x no longer exists. However, the rogue has the First Strike ability; if he can hit any orc that hasn't acted yet, he'll still get sneak attack.
(Note that even if some of the orcs beat his initiative, if he beat one of their initiatives, he can target that orc and get sneak attack.)
Run combat normally from that point.
Now someone point out all the errors I made; it's a good way for me to learn
