I remember seeing a book - I believe it was called "The Meaning of the Blues" - at my local library. It went into quite a bit of depth about the society, folklore, superstition, and other areas of life that made a lot of these phrases clear, although it didn't necessarily define specific phrases. Sorry, I don't remember the author. Meanwhile, there is a wealth of information in the heads of Mudcat forum participants and we like to show off. I for one never hesitate to state my opinion and my dimly recalled memories as fact:-) Therefore:
dust my broom - seems to be a euphemism for leaving - I could be wrong on that.
jelly roll - literally a type of pastry which is apparently rolled up like a log when baked - therefore a phallic symbol. "Jelly" sounds like the word for semen in some African language which lends to the symbolism.
mojo - a fetish or "love charm" meant to bring or keep a lover under the control of the one who owns it. Sometimes called a "mojo hand" - I wonder if this referred to something like a "lucky monkey's paw" or (in areas where there aren't monkeys) rabbit's foot. Other similar objects referred to in the blues are a black cat bone (a certain bone from a black cat which has been killed in a ritualistic manner), various roots and dusts, and "John the Conqueror" which was apparently a mass-produced novelty item. My feeling is that the word "mojo" is related to mumbo jumbo, an English corruption of the name of an African deity (M'amba D'jama ?) who's function, if memory serves me, was to ensure marital fidelity.
My observation is that "mojos" in pre-war blues were used by women trying to control their men ("My baby's got a mojo, she's trying to keep it hid/McTell's got something to find that mojo with") but in post-war blues, they are used by men trying to control their women ("I'm going down to Louisiana, get me a mojo hand/I'm gonna get all you women under my command"). This reflects the increased sexual liberation of women precipitated by the social upheaval of World War II.
ride the blinds - the practice of riding a train or bus without paying as in hoboing. I think it refers to getting on in a "blind" spot - an area beyond the view of the conductor, engineer, or bus driver.
Anyone else care to take a shot (or a potshot)?