The first few sentences you write are your lead. Most often your first draft lead is crumby and even awful. Like these:
Awful First Leads
One day…
I woke up…
It was a sunny day…
It was a rainy day…
I dreamt…
I think you get the idea. Reading lots of examples of leads from your favorite books can be helpful. Knowing the types of leads can also be helpful:
Types of Leads
Dialogue between characters
Inner thoughts
Setting description
Character description
Start at the end
Action
Question
Just like when drafting you write loads of pages. When writing leads you do the same! Try to write ten different leads for the same piece!