You can start the siphon with clean water or sanitizing solution. Just completely fill the hose with liquid, put your CLEAN thumb over one end, and submerge the other end into your beer. As long as the hose remained filled with liquid, and you have the "outlet" end lower than the end in your beer, the siphon should start as soon as you take your thumb off of the end. You can drain the water/sanitizer into a separate small container and then quickly move the siphon hose to your carboy if you like.
No sucking because your mouth contains lactobacillus bacteria which can VERY easily infect your beer, making it taste sour and nasty.