Mhm, well if you're to buy 2 decks, one would assume you'd get one of each, as there is two decks out at the moment, Blaster Blade and Draconic Overlord.
Blaster Blade is a Royal Paladin deck, so when you buy boosters you will be looking for support for them. The main things you will want to get your hands on early are Shield Maiden Isoltx3, Barcgalx1, Blaster Bladex3 and as many Alfred, King of Knights as you can possibly get (he's been hard to get down here, only 6 have been pulled in the entire territory, but Melbourne has pulled heaps, so you may get lucky). Your starting triggers are good, but as soon as possible you want to swap in 4 of Future Knight Llew, as his effect will help you Superior Ride your Blaster Blade (terms will make sense when you play). If you want to go with 4 criticals and drop all your Eponas for Llews, up to you, but my friend who plays the top RP deck in the ACT runs 4 Llew 2 Epona, because criticals can win the game easily. Up to you in the end, because you have to lose something to.
After you get Barcgal, the extra Blaster Blades, Isolt and Alfreds, your focus should be on finding the other RP support cards, like Demon Slaying Knight Lohengrin, who you want 1 or 2 of, and you might even want to look into adding a third Solitary Knight, Gancelot, to help you get those Blaster Blades out early. From then on just look for whatever RP you can find and put whatever suits your play style into your deck.
The other starting deck is Kagero with Draconic Overlord, so your first goal is to find Lizard Soldier, Conroe, as he is your basic starting vanguard, like Barcgal, so you'll only need one of him. For support, you'll be looking for Wyvern Guard, Barrix3 and Embodiment of Spear, Tahrx4, again, to replace or work alongside your current criticals. Kagero is a very offensive heavy deck, so extra critical triggers may work in your favour more for Kagero then it does for RP. The starting Kagero deck is full of basically most of what you need, so once you find a Vortex Dragon or two, you'll be set to play high level games.
For advancing your deck, you want to find Dragon Knight, Alephx4 and Embodiment of Victory, Alephx3. They are the best Superior Ride out at the moment, letting you get to Grade 3 on your second turn, so keep an eye out for them. You might want to get some Dragon Monk Gojo for hand control, but he's not needed and most people aren't too fussed. Until set 2 comes out, that's really all you need to do for Kagero, and you can get a very powerful and viable deck very quickly out of them.
Big thanks to JoeTurtle for this one^^