I just have a quick question regarding tests, and as a GM, when I should be calling for them. I'm fairly new to RPG's in general, I've played a few DnD sessions before but nothing more. The group I'm running through now are even newer than that, sitting down and rolling their first Deathwatch characters was the first exposure to any RPG ever. So needless to say, they are still getting used to this style of game play.
Over the past few sessions, its been running fairly smooth, and everyone has said they are having a great time. I've really only been calling for the odd lore test, and quite often, perception checks here and there, nothing more. Moving into a new adventure however now, I want to show how import skills are to their characters, rather then have them continue just buying talent and characteristic upgrades.
The question I have is, when should I call for a test, and when should I wait for them to ask to make one? An example would be in: In this new adventure, there is an NPC who approaches the group, asking them to come help rescue a bunch of others who are trapped in a building. The NPC is deceiving the players, luring them into a trap, and I'm obviously hessitant to ask the group "Take a Scrutiny test", to see if they can tell, becuase then its fairly obvious. However, I know that their fundamentals aren't there yet, and there response will be to follow, without hesitation.
In situations like that, should I just let the players fall into the trap, then let them know the error of their ways at the end? Or should I prompt them by saying this could be a trap?
Thanks very much!