Luck should never be a factor in your deck unless it is an added bonus (Fainting spell). I just started pokemon last year. I went to my first Cities this year. I wasn't expecting much from myself. But I did lose quite badly.
This was due to my : Inexperience, Relying on luck, major misplays, competition etc. Now you must eradicate each and every possibility I stated and more. I made a deck which relied on luck. This mean't that I had to rely on my opening hand which was never good a good idea. Even when I did start playing I made major misplays, lost concentration and was not really confident in my abilities.
Add all those together and you surely have a recipe for disaster.
But something came out of it which was worth a lot to me. Learning from my mistakes.
This then made me make these rules which I make sure I recite before I make a deck and before I go to a tournament.
1. Play a competitive deck
2. Make sure that it is near impossible for luck to ruin your game
3. Consistency is paramount to any deck
4. Study your deck
5. Be comfortable with your deck
6. Always concentrate. I know it is obvious yet sometimes people forget to do a certain move or don't read the situation properly
7. Be 3 steps ahead. This is the same as chess. If you lose a pokemon be ready to fight back harder
8. Finally make the right choice. Another obvious one but the right choice will always win you the match.
I know these rules may seem n00by but I am a beginner. Don't be harsh