How I play skills in my GURPS game.
Skill rolls tell you how well your character executes your actions, not what actions your character takes.
The player tells me what the character is doing, the skills and skill rolls tell me how well you do it.
The player announces an action, the character executes it
An action must be a discrete thing you're doing, stated in a way that describes what you do. It can't be a goal or aspiration. It can't be a simple statement of rolls made.
So "I roll Perception!" isn't allowed, any more than "I roll Broadsword!" or "I roll 'to hit'!" - none of those tell me anything about what you are doing. It's not an action, it's a description of the mechanics.
So how to state an action?
"I disarm the trap" or "I look for secret doors" or "I use Physician" are about as valid of an action as "I slay the monster" or "I kill the bad guy" is. That tells me nothing, really, about what you're doing. That's a statement of intent or a goal; a mission statement not a description of how you're getting there. This is especially true in GURPS, in my games, where "I slay the monster" doesn't tell me what weapon, what hit location, what attack mode (thrusting? swinging? Swinging the head or the peen? Doing something else?), and any other positioning, movement, or options you're taking.
"I step up and swing at the guy in front of me, at his neck" is better. Same with "I'm trying to bend back or otherwise break the poison needle in the lock" or "I tap along the walls to hear if they sound thinner in one spot" or "I'll bandages up his arm wound with my Physician skill and try to clean it out." Even something basics like "I look at the ceiling" is okay. All of those can end with "and I have a XX in skill Y." The mechanics come in once I know what you're doing. They'll end with rolling Broadsword, or Traps, or Search, or First Aid, or Perception, but they start with a statement of action.
You describe the action in real-world terms as well as game terms, to let me know what you're doing and how. Then we let the dice (or GM judgement, sometimes) decide how that all works out.
Why this way?
- it preserves the importance of "being there" and playing the character. Your decisions matter, and your ideas help or hinder you.
- it preserves the value of skills. They let you play someone better or worse than you at the action. The character's ability to execute means that there is a real benefit to being an agile, light-fingered thief or a frighteningly skilled brute of a warrior. And a cost to being bad at things. Just because you say "I bend back the poison needle" doesn't mean you succeed. Just because you say "I swing my sword at his neck" doesn't mean you hit.
- it preserves the differentiation of "player" from "character." Just because you, the player, know what you want to do doesn't mean this particular character/playing piece/paper man can do it. It makes the character on the paper both more and less than what you're capable of.
What about what my guy knows?
It's harder to do this.
Knowledge skills are a little trickier, because it's often a valid question, "What does my character know about this?" Maybe having Hidden Lord (Elementals) means you know something about fighting elementals. Maybe have Physician tells you stuff about doctoring that you don't know but your character might - "Is it normal for that to happen, does my guy know that?" Even knowledge-based used of a non-knowledge skill (say, Boating or Swimming) might be valid - you want to know what kind of make the boat is, or how swimmable the water looks.
In those cases, you still need to specify what you're after, not just say "I roll Swimming to see if the water is okay." It's too vague and hands over the real fun of roleplaying - being someone else in a shitty situation you wouldn't want to be in - to a simple roll.
Generally, though, if your question boils down to "Hey GM, tell me what to do!" or "Hey GM, tell me the answer!" it's not going to work.
If it boils down to "Hey GM, does my guy know the answer to my question?" or "Hey GM, do I know this is really stupid and shouldn't do it?", it's okay.
And of course, so is any question of "I try [some action], how well do I do it?" like "I go to the library and read up on elementals, can I roll Research?"
And that's basically how I run skills.