Throw out b1, it'll counterhit.
Easiest to hardest for match practical stable combos that give Snake Eyes - other routes will do more damage / carry but may not give Snake Eyes; these are what I go for if I want the buff.
End with b1~f2,2 for slightly (1-2) more damage but less carry.
1. b1, 1+2, 1, 2, b2,1 ~slither b+2,4 (ender)
2. b1, b2f4, microdash 2, b2,1 ~slither b+2,4 (ender)
3. b1, b24, dash 2, b2,1 ~slither b+2,4 (ender)