To be honest, I personally think that the only reason your musical style is relevant is to see if it fits with the venue. Also, I doubt any tape (however long or short) will be incentive for someone to contact you and book you.
Be focused, pick the clubs/venues you think would fit with your style of DJ-ing and music. Go out to them for a while to test that hypothesis (i.e. was I right in assuming I’d fit in here?). While you are there, go early or stay late (or both if you have the stamina). While it’s still early or while it’s slowing down, make contact with people like the bar staff, the door man, the resident DJ, the manager, the owner. Not to shove yourself down their throat, but just so they get to know you. After knowing them for a bit, drop the fact that you are a DJ and the reason you are coming to the place is that you like it a lot and you would really like to play there sometime. Could they let you know if something opens up. Leave your card with them so they know how to contact you. You can invite the bar staff to come see you at the place you are already playing on their night off for example.
In short, network, get personally involved. Of course, make sure if you have a website or facebook page that they can find some vids and audio of you playing, some bio background. But that is AFTER they know (about) you, not because they are looking for someone.
Hope that helps some. My three cents worth as usual.
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