get on some old clothes...get a flashlight...or a 500 watt halogen
lamp.......

get a long stick to move cobwebs etc out of the way.

go into crawlspace and make a lot of noise so that if there are any
creatures ...the noise will scare them away from you.

hunt for leak or signs of leaks.....

DO NOT get a neighborhood kid....if there is broken glass or a piece of
rusty metal under there, the kid will find it after it embeds itself
into him......lawsuit or worse could follow

One last warning....IF you see a creature and its young under there
remove yourself as quickly as possible....man is no match for a coon or
possum in a 2 foot crawspace.

DONT worry about snakes....they will move if they see or feel you
coming...make noise...smack the ground with a stick...they will move on