field theory - Sign of Feynman rules with derivative couplings

Feynman rules for derivative couplings always make me confused. For example, the derivative in $gV^\mu\phi^+\partial_\mu\phi^-$ will give you $\pm ip_{-\mu}$, where $\pm$ depends on whether the particle is outgoing or incoming.

I found "$-ip_{-\mu}$ for incoming" in Peskin & Schroeder's QFT book, BUT I also found "$-ip_{-\mu}$ for outgoing" in some other literature. So I'm wondering if the latter one is wrong. Or are they just in different conventions so that we can choose either of them?