Unlike an eclipse, a transit will not appreciably reduce the amount of light coming from the sun. Venus will be a very small dot crossing the upper right quadrant of the sun, so you will need a long focal length and expose as though you were photographing the Sun. The eclipse will still be in progress as the Sun sets from Florida, so if possible you will want as low a western horizon as possible. You should have an hour and a half to two hours (depending on your western horizon) or so from the beginning of the eclipse at 6:04 EDT until the sun sets, so there's plenty of time for multiple setups, exposures, etc. -- no need to hurry with this one!
As always, do not look at the sun without adequate eye protection! Use a #14 welder's glass, a purpose-made solar shield or solar glasses, etc. Exposed film and neutral density filters do not block enough solar radiation to protect your eyes -- don't use them! Do not look through a lens at the sun, even for a moment: eye damage will result instantaneously. Do not look at the sun's image on your ground glass with a loupe or magnifier -- you will damage your eye!
Be safe and good luck!