I have changed mine a few times depending on where I have been flying and what rwy lengths im dealing with...
in PNG it was a matter of picking a speed but also a decision point as a physical point on the strip and then an acceleration time to blue line due to the usual drop off's etc. flollowed by a performance check for continueing...
i.e: If I have an engine failure or malfunction before my decision point i will stop. After my decision point i will control the aircraft accelerate mixture pitch power flap identify dead leg dead engine verify with throttle and feather... with positive climb i will continue to xxx strip (low pt) otherwise i will pick a landing point within 30 degrees.
With a normal length strip or with second crew i have:
i.e: If I have an engine failure or malfunction below xx (toss)kts I will stop. After xx kts and gear in transit i will conduct the drill - mixture pitch power confirm gear up flap up identify dead leg dead engine confirm with throttle, confirm with crew... maintain xx (selected blue) kts and ball in the middle if not climbing look for a field within 30 degrees. With positive rate of climb conduct a circuit in the direction of the live engine and return to land (dependant on vmc imc and local terrain).
but im just reiterating what others have said just learn something relevant to your aircraft or sop's... but remember you dont want it to have to change to much as you will generally keep it for a number of years once you've learnt one...
sit in the aircraft and touch drill your way through, doing everything as smooth and fast as you can without a mistake before you even start the engines, or your lesson, and you will be sweet...