I did my best to try and keep to the cards before the GX series. No heroes in my deck thank you.
I do like to think I had a pretty powerful deck, though I was more about trying to get as many awesome cards as possible. Like how I had all 3 sphinxes and the pyramid of Light, Redeyes Darkness Dragon, VWXYZ Dragon Catapult Cannon with all the cards for it except XYZ Dragon Cannon. I even had Gate Guardian.
Along the lines of strategies, I always played to get as many strong monsters on the field as possible. Namely Return from the Different Dimension and the strongest 4 star monsters and ways to summon the even stronger monsters as fast as possible while ensuring my opponent can't do anything. At one point I was the best in the school. Once my deck even got stolen and found by my Rival (yea I had a Rival) who threw a few of my cards into the river next to the school.
Since then though I've lost most of my cards, but I still have a small deck which can hold up to some of the better decks and I'm glad I still have my first card, Dark Magician from Yugi's Starter Deck.
I also recommend watching YGOTAS (Yu-Gi-Oh the Abridged Series) on youtube if you're looking for a great laugh.
Synchro What?