Use a saddle to ride a pig, then have the pig get hurt from fall damage while riding it.

Smelt wood trunks using charcoal to make more charcoal.

Befriend five wolves.

Acquire diamonds with your iron tools.

Construct a Dispenser.

Dye all 4 unique pieces of Leather Armor.

Use Shears to obtain wool from a sheep.

Stop starvation using Rotten Flesh.

Bake a cake using wheat, sugar, milk and eggs!

Catch and cook a fish!

Craft and place a sign.

Wear a full suit of Iron armour.