Purchase aloe vera leaves from your local store or break off aloe vera leaves from a plant. I bought mine from my local Asian grocery store.
Wash leaves to remove any dirt.
If dealing with a big leaf, slice a portion off of the leaf so it's easier to work with.
Slice the spikes from the side of the leaf.
Peel the top layer of the leaf. If the leaves are fresh enough, you can peel them with your hands. If not, you can use a knife (But you really shouldn't be using unripe leaves in the first place).
Use a spoon to scope out the aloe vera flesh.
Blend in a blender. Strain before using. To make aloe vera juice, blend the flesh with pure water.
Transfer to a glass jar and refrigerate. Keeps for up to 2 weeks, without any preservatives.