Just a recap, you'll probably need the band, the venue, and the engineer to all be cool with it cause any one of them can deny you at their whim, so kissing ass is important all the way around REGARDLESS whether the band is supposedly cool with SBD patches.
Next, make sure you can handle 2x1/4", 2xRCA, and 2xXLR outputs from the SBD because you might see any one of those connectors.
Also, like said above, don't expect the holy grail from the SBD, it might sound too clean and way out of balance depending on the music and venue. Remember, they are mixing to make the room sound good, not the board outs.
And don't forget to TURN OFF phantom power on your inputs (if you have that) cause you never know what might happen at the SBD if you send it power.
Lastly, there's been some talk above about plugging yourself in (with permission), but take it from me, whether you are a newb or not, I think's it's always best TO NEVER EVER TOUCH ANY SHIT THAT ISN'T YOURS at the venue. The minute you touch it and something goes wrong, whether it was your fault or not, it's going to get blamed on you so don't even go there. Ask permission and LET THEM plug you in, and LET THEM unplug you at the end, and LET THEM change the levels they are sending you. Everyone will be happier with that protocol (of course there are some exceptions to this rule, but I might argue they are the exception, not the rule, especially for a newb).