Right now, getting prebuilt is expensive (1500g) and unlikely to be achieved unless after months of mirage master. There is a sales discount supposedly on Friday but I assume you don't have enough gran anyway. Be patient. As a free player, it's going to be really really slow at the beginning because you don't get new cards. If you are not saving up, the 10g lotto is your friend for at least a month or two. Then, it's packs or prebuilts.
On the bright side, they are soon giving out 3x 5*. I don't really suggest you recycle them if you have long-term plans for playing those cards in the future. Otherwise you can get 900g from recycling them (again, not really recommended).
Gon's guide (theory): viewtopic.php?f=13&t=10218
Gon's example decks (aimed as low rarity as possible): viewtopic.php?f=13&t=6455
harvest's archetypes for Falkow: viewtopic.php?f=15&t=8293
Also, replay forums to watch games: viewforum.php?f=33
Or simply go on Folrart to watch games as spectator.