Here's a great deck that I've had a lot of success with online. As of the time of this writing, all of the packs that these cards come in a available in the game. Pretty much every card in this deck takes life points away from your opponent. When I use this type of deck, I never atack, yet I win at least 75% of the time.

Effect Monsters:
3 Poison Mummy
3 Gian Germ
3 Cobra Jar
3 Des Koala
2 Princess Tsurugi
2 Lava Golem
3 Spirit Reaper
1 Cannon Soldier

(Any of the above can be replaced with cards that deal damage to your opponent's life points when flipped or destroyed, except for the Spirit Reaper and Lava Golem, I recommend keeping those)

Spell Cards:
3 Chain Energy
3 Toll
1 Dark Snake Syndrome
1 Enchanted Arrow
3 Wave Motion Cannon
1 Restructor Revolution
1 Tremendous Fire

(Only replace these cards with ones that deal direct damage to your opponents life points such as Poison of the Old Man)

Trap Cards:
1 Ceasefire
1 Nightmare Wheel
2 Secret Barrell
1 Gravity Bind
1 Ring of Fire
1 Just Desserts

(I try not to use as many spell cards because of Jinzo. You can add more of the above cards if you like. I recommend not using more than a total of 20 spell/trap cards combined.)

To use this deck, try to go first. I've noticed that Restructor Revolution and Secret Barrell get dealt to me in my first hand quite often. If you go first, Restructor Revolution can immediately deal 1000 points of direct damage to your opponent's life points and Secret Barrell 1200 life points without your opponent being able to do a thing.

This deck gives you basically 2 ways to win. Start out just by dealing as much direct damage to your opponent as possible with your effect, spell, and traps that deal direct damage. If you don't get the cards you need you still have another out. Use Spirit Reapers to defend yourself (attacking cannot destroy this card) and back that up with Gravity Bind (Level 4 and above monsters cannot attack.) Then summon Lava Golem to your opponents side of the field. (This will take away 1000 of your opponents life points each turn.) Combine this technique with the wave motion cannon, and you will win in just a few turns. You don't necessarily have to use the exact recipe listed above but try to keep it to...

40 Cards
  20 Effect Monsters
  20 Magic / Trap Cards

Make sure nearly every card in your deck deals direct damage to your opponent one way or another. Any other cards (keep to a minimum) should only be used to cripple your opponents ability to attack.

Check out my store at http://stores.ebay.com/crewelectronics for details on what cards come in what pack.