Wagered Actions
When you're doing something familiar, you can focus on a specific outcome. This lets you wager some of your EL toward a specific effect, but those dedicated points reduce your chance of success.
Remove the wagered points from your EL before rolling. If your action succeeds and generates any effect after opposition/resistance, add your dedicated points to the intended result. Successfully wagered points are applied after opposition. The wagered points are counted as having succeeded only if the roll succeeds without them.
Residual Effects
This is the mechanic used for Persistent Boosts. Wager the points you want on the Boost and succeed with what's left after they are set aside, get a named bonus that can be added directly to the EL of other relevant rolls for the rest of the scene.
This can also be the setup for a separate standalone roll. If you set someone on fire, the fire continues to attack on its own. Instead of a Persistent Boost, it is a residual condition that gets to make rolls of its own to burn the target, while he rolls to control the damage and put it out.
Contingent Splits
When action B requires you first succeed at action A. If A happens, roll B with the points set aside for it - otherwise they are wasted. This is technically just a normal split, but it's a wager since you have to succeed on the first roll to get the second one. If you want to catch the incoming potion bottle and throw it back at the evil alchemist, you don't get to throw it unless you succeed in catching it without it blowing up.
Dedicated Effect
This is the "called shot" rule. Wager points of your EL and specify what you are attempting to do with them. If the roll succeeds without them, those points all count as having succeeded, and you get to specify something about the effect they cause. You can say those points are dedicated Injury instead of just Complication, even when unarmed - narrate the justification, such as trapping a punch and overextending the elbow to break it. Name the result so it can be used in the narrative. As long as what you want is reasonably something that might have happened anyway with the narrative excuse, it's good.
If you want to do something that has other side effects, you must allocate points for those as well. Poking someone in the eye to cause Injury seems like it should also give them a Hindrance since it's hard to see now. That would require another allocation of points wagered, but it isn't necessary; just narrate the impaired vision into the reduced effectiveness due to the Injury itself.
You can never dedicate more points than your rank in the relevant Role.
Dedicated Effect Example - crunching some numbers
A warrior with EL10 wagers 3 points as dedicated Harm.
She removes those from her EL, leaving 7 for her attack roll.
She rolls a 5.
Her target defends with a 4, leaving only 1 point of effect, but her 3 points of dedicated effect are all treated as successes and are added for a total of 4.
If the target uses their armor to boost their resistance EL by 1 it cancels her only point of unmodified effect, so the wagered points are wasted. You don't get the advantage if you can't succeed without them.