Aspects in Fate (and by extension Spirit of the Century and The Dresden Files RPG) are an incredibly powerful tool, but like most tools they can be hard to use without a little familiarity. Obviously, if you're already very comfortable with their use then advice in applying them is of only limited use, but maybe you'll find this interesting anyway.
Players tend to be very enthusiastic about using aspects once they feel they can, but there's often an initial period of hesitation, where the player is mostly asking the GM whether or not he can use an aspect. It may be a step on the learning process, but playing mother-may-I with the GM is rarely something that gives players an excited first impression.
More problematic is the GMs end. The process of compelling aspects is one of those things that is harder to explain than do, and the process of explaining it can often end up seeming needlessly arcane. The fact that it works well at some tables does not erase the fact that it's overly tricky on others.
So with that in mind I'm going to propose a model of aspect use which will hopefully solve both problems. This is of especial use for new players and new games since it will have an impact on the type of aspects that people choose (or more specifically, how they phrase those aspects).
In this approach, we no longer explicitly refer to compelling, tagging or invoking aspects, and in fact there are no such actions. Instead, we simply treat aspects as magic words.
For a player this simply means any time he actually uses the aspect as part of his description, as part of what his character says or generally as part of play, he can spend a fate point for appropriate bonuses.
I come at him fast and furious.
"Jet's in trouble!"
I look over the scene cautiously.
When spending for effect, which is to say, spending a fate point for something other than a bonus, simply make it part of the phrase.
I'm pretty well prepared, so I'm sure I've got some spare batteries here somewhere.
I've got a girl in every port and this one's name is Trixie
I've been up for two hours already. I'm a light sleeper.
And that's all the player needs to know. Say the word and slide the fate point forward. No need to ask the GM or check if it's ok. Just go forward. Now, yes, a GM may raise an eyebrow if something is totally out of line, like using well-prepared to justify having a rocket launcher in a boy scout pack, but things like that don't actually happen unless someone is being a tool, so don't sweat it.
On the GM side, the same logic applies. These are magic words, and every now and again you will start a sentence with one while sliding forward a fate point. If the player takes it, that's their cue to pick up the thread. If they don't then close it off. For example:
This guy has been riding you for the whole trip, trying to get under your skin. It would be easy to get angry...
At this point the GM slides forward the chip, if the player takes it, then the player proceeds.
Yeah, he gets me so pissed off that I pop him one in the dinner car over breakfast.
If the player declines, the GM proceeds, taking back the chip.
...but you manage to keep a cool head.
Yes, for the GM's part there's a bit more non-verbal communication, but not enough to break the flow.
Long time Fate players will also notice that in this case, the player was given leeway to make trouble for himself with the aspect. This is not mandatory - the GM can frame the aspect in much more detail - but unless the player is in a position where it might be hard to come up with a way the aspect might complicate things, it's often worth leaving such trouble in the hands of your players.
This model is fairly flexible in terms of what aspects it supports - people, places and things can all be named dropped ("If there's one thing Master Po taught me it's...") but it will get a bit gummy with more poetic aspects. The harder it is to work the aspect into a sentence, the harder its going to be for it to come up in play. Players looking to use this approach in existing games may need to consider rephrasing some of their aspects so they flow more naturally.
1 - Yes, adverbing it up or making other reasonable transformations are entirely valid.