Okay, remove all DLC and play the game as normal. Refuse to engage in any paralogues or skirmishes. This way you only get experience through the normal chapters. Refuse to buy any extra weapons apart from stuff you get from enemies and characters through recruitment. Do not use Fredrick at all in lunatic. Achieve low turn counts. As in go for the fastest turn count possible.
Oh, and do not play on lunatic, play on lunatic+. All enemies will be have 1-2 skills which are sort of broken. These skills are randomly assigned mind you.
Vantage+ Will always attack before you in all engagements.
Aegis+ Halves damage from bows, tomes and dragonstones.
Pavise+ Halves damage from swords, lances, axes (includes magical variants) and beaststones.
Hawkeye+ Avoidance is not possible. You will be hit.
Luna+ All attacks will either half your defence/resistance when calculating damage.
Here is an example of the stupidity that will ensue.
http://www.youtube.com/watch?v=Ku-PMHcFPAY