There are a couple variations that can be made with the free red/green deck. The deck can be highly creature oriented or creature control heavy.
Cards that specialize in a theme (goblins and wolves) should be culled out, since the deck would be hard pressed to carry any specific creature theme. Taking out Super Swift Boots and Llanowar Charm right away.
Keeping the efficient creatures, creature enchantments, and spells, the deck starts to take shape:
Berserker of Bloodridge x3
Goblin Fodder x4
Raging Goblin x3
Headfirst x1
Lightning Bolt x3
Seething Song x3
Threatening Lunge x3
Elvish Warrior x3
Llanowar Elf x3
Lone Wolf x2
Pathfinder x4
Elvish Agility x2
Giant Growth x3
Oakenform x3
This selection gives 40 cards to try the deck.
Variation example
Some of the less efficient creatures (Berserker of Bloodridge) can be switched out for more creature control cards (Entangling Vines and/or Plummet) or better cards from the free booster.
Of course, this is just one deck idea and the deck can either be a green deck with a few red cards thrown in or vice-verse.
Complete red/green list