Note: There are many "right" versions of this sign.
General sign for first (the most flexible).
"First of all"
This is a variation of the same sign. Notice how the index finger
moves past the thumb instead of stopping at the thumb like in the other
Both ways are okay. I suggest you do the first variation, but that
doesn't make this version wrong. See below for even more ways to sign
This version brings the index finger to the thumb where it makes contact
but doesn't go past.
Another version of "first"
First as in "the first one in a series."
First place in a competitive tournament:
Second place in a tournament: