The key concept to being a good fake Christian is perfection. We are called to it. After all, Jesus was perfect, so you must look perfect as well. Note the words "look perfect". Of course you can't be perfect, but you must look perfect. And if you try hard enough to look perfect, you will convince your mind and those around you that you are perfect.
Perfection is a goal that is universal to all mankind. We all desire it and it some ways worship it. For us good Christians, the worldly goal of perfection is made holy, no matter if its truly from God or not. Obtaining the look of perfection has perks in both worldly and holy areas of life, so more power to you.
One great tip on how to look perfect. Do not admit wrong, no matter what. Mrs. Fake is an expert at that. She loves making excuses, twisting words around, and denying actual actions or words. Make it the other person's fault or at least a "misunderstanding". Blame others as much as possible, though keep it subtle as to not attract suspicion.
Perfection gives you a pedestal to look down on others, especially the weak and persuaded. Gather a group of "followers" made up of gullible people who will sway at your every word and thus amplify your greatness. If you are skilled enough, push perfection on the younger generation and guilt them when they fail. That will give you ultimate power. At this point, looking like Jesus is just a ruse. After all, you're a fake Christian.