If you're trying to get through the game then find Crow, partner with him and take him to the shop. This unlocks his pack which you can use to build an almost complete Blackwing deck. Yeah it's a little dry but it's reliable and can make the game a veritable walk through the park.
My advice First, go to the deck menu and switch to the 2nd starter deck (triangle - deck menu - deck edit - triangle - deck & recipe menu - load recipe). it is tons better than the first one. Next duel some randoms until you find someone you can beat and get some DP from them. After that buy a bunch of the element of the day decks depending on what you want to build, they are available on different days (in game, not IRL) use the triangle menu to end days until you get to the one you want The Truth's Within Me (dark, steelswarms and ally of justice, available on monday) I'm On Fire (fire, laval, flamevell and jurrac, tuesdays) In My Element (water, ice barrier, wednesday) Butterfly Effect (wind, dragunitiys and mist valley, thursday) Shade of Light (light, fabled and worm, fridays) I Walk the Earth (earth, gem-knights, naturias and some x-saber, saturday)
For some easy early game decks I suggest Jurrac, Dragunity or Gem-Knight, but that is pretty much just personal preference. After you have a half decent themed deck then you can unlock the row 1 and early row 2 packs by buying them (ie Applied Monsters requires you to have 30% of Monsters for Dummies)
Once you have the top spell/trap/monster packs unlocked (Ultimate Monsters, Deluxe Spells, Supreme Traps) you can build a basic glad beast deck and go farm a duelist by the name of Maia. Go to Martha's Place and talk to blister, pay 500 to put a tracker on her and 600 to revel her for a week. Her final countdown deck is almost no match for even the weakest glad beast deck (you need 1 bestari and at least 1 gyzarus and as many test tigers as you can find, after that you can do whatever you want, just keep summoning bestari and gyzarus to blow up her cards) and she usually gives out 1500-2000 dp.
After you have some DP saved refer to http://www.gamefaqs.com/boards/997448-yu-gi-oh-5ds-tag-force-5/57079380 http://www.gamefaqs.com/psp/997448-yu-gi-oh-5ds-tag-force-5/faqs/61339
to see how to unlock decks and what they all have in them and go nuts with deck building.
Your other option is what Windstorm101 said, partner Crow, get blackwings, farm. But I find that severely boring, also you will need to do a bit more dueling with the starter decks to be able to afford to buy enough packs to build the deck
I'm seriously laughing my ass off right now at those names. I wish I was Maleysia's boss, so I could be all like "IMMA FIRIN' MALEYSIA" - mootoast