Bros: What handshake do I do?!

I'm an 18 yr old guy, and I never know which handshake to do with other guys my age. Some guys do the "slide your hands together starting from the palm to the fingertips," some do the "grab hands and pull in, touching shoulders," some do the "looks like a handshake but you wrap your hands together and then slide them apart," etc. HOW DO I KNOW WHAT HANDSHAKE THEY'RE GOING TO DO?!