songs to learn slide playing with

got one of these glass slide thingamajiggers and tuned my geetar to open G. trying to get it to sound right w/ out the buzzing and squealing and starting to get the hang of it. any suggestions on songs to start off w/? Here's a list of songs I currently am trying to learn:

Bad to the Bone ~ George Thorogood
Mean Old World ~ Eric Clapton
Mr Banker, Curtis Lowe, Freebird intro ~ Skynyrd

These songs are kinda advanced for my slide playing ability, i was hoping someone could suggest something easier like maybe a blues song. What are some goodand easy Muddy Waters or Robert Johnson songs to play slide on?