The thing to keep foremost in your mind, as Wired has already mentioned, is that there's always someone on the other end of the conversation. Try to avoid rolling after every sentence and instead focus on one roll per general idea or action. If you spend a few lines trying to convince someone to loan you some gold make a single check at the end. You can then wait for their opposed roll or reaction. Skill checks during adventuring is more free-form. Many characters like to RP a Spot check before opening a secret door. The section below has suggested DCs for such uses, but I've noticed most players still open the door even after failing their own DC
When rolling between PCs it's really up to the two of you to make a decision on how to roll. As far as general use goes, there are a few trends which have emerged. Most of them are based on the P&P ruleset or other experiences. Non-opposed rolls should either be rolled against the general area or some inanimate object. Targeted rolls often use the other PC or NPC as a target.
Non-Opposed Rolls
These are skills or checks that depend on the situation and not another PC or NPC to determine the outcome. This could be anything from a Strength check to searching an area.
What you roll depends on the type of activity. If it's something trainable it would be listed under skills, otherwise it would either be a stat check or saving throw. Stat checks are used for something that would normally be a skill, but is either untrained or not available as a skill selection. One example of this is Swimming, a strength-based check which doesn't exist in NWN2. Anything else would be a saving throw roll, and generally takes into account the ability of a person to get better at something with age. This includes diving out of danger's way (ref save), shrugging off poison (fort save), etc.
DC Examples From the SRD
- DC00: Very easy - Notice something large in plain sight (Spot)
- DC05: Easy - Climb a knotted rope (Climb)
- DC10: Average - Hear an approaching guard (Listen)
- DC15: Tough - Rig a wagon wheel to fall off (Disable Device)
- DC20: Challenging - Swim in stormy water (Swim)
- DC25: Formidable - Open an average lock (Open Lock)
- DC30: Heroic - Leap across a 30-foot chasm (Jump)
- DC40: Nearly impossible - Track a squad of orcs across hard ground after 24 hours of rainfall (Survival)
It also helps to put it in perspective within the D20 system.
- DC10: The general population (Ability score of 9-10) should have a 50/50 chance of succeeding at this roll.
- DC15: Harder to accomplish, 25% chance of success for a standard person.
- DC20: 5% chance for a normal person. Above-average natural abilities really start to show here
- DC25: Only an exceptional person (one who has a 20 in the relevant stat) or someone who's trained in a skill would be able to make the check.
- DC50: Defined in D&D as an Epic-level skill check. Someone would need an ability far in excess of what's achievable in a standard lifetime to make this roll.
Opposed Rolls
These are a bit tricker since it's a roll between 2 (or more) PCs or a DM. Most of them function like you would expect, with a few exceptions.
- Bluff --> Sense Motive
- Disguise --> Spot
- Hide --> Spot
- Move Silently --> Listen
- Sleight of Hand --> Spot
The major exceptions, and ones which seem very popular on Dasaria, are Intimidate and Diplomacy. Neither one of these was meant to be used against a PC, and as such were not designed with an opposed roll. Many characters have informally settled on a Will saving throw to show their resistance to such an effect. Another method is a direct opposed roll (Intimidate vs. Intimidate or Diplomacy vs. Diplomacy) to throw their threat or argument back in their own face. This can be exceptionally fun when trying to convince a crowd of people who they should follow.