First of all, you must accept arrest as the possible price of activism. Once you have accepted arrest as inevitable, then you can decide to get arrested on your terms, not theirs. You are then free to crank the dignity and fun level up.
Learn from others. Join the discussion at http://votestrike.ning.com forums, and get in touch with activists in your area.
Pick the right time and date. A good time to start your event is 2pm. Any earlier and you will have smaller crowd. You don't want to compete with other major events that might draw away your crowd. Try to work synergistically; perhaps you can time your event so that you get people who are just leaving an earlier event, like church.
Make a poster. Find someone who can design a poster with eye-catching graphics and easy-to-read text. List the event's time and place clearly, as well as attractions like speakers. Posters stay up longer with a 10:1 mix of water and wood glue. They stay up even longer if you haul a ladder around with you and put them high up. Have smaller posters ready for small poles.
Print a leaflet (flyer) to hand out at rock concerts, skate demos, festivals and other culture activities. Distribute posters and leaflets to all retail stores, clubs, alternative and campus radio, and newspapers.
Print as many posters and leaflets as possible, but use what you print. Distribute them through school, work, and activist networks. Posters and leaflets should be printed and ready at least eight weeks before your event. Your entire city or region should be covered.
Make banners. Banners can be hung behind and around the speakers and any musicians. They can also be carried during a parade. Simple slogans always work well.
Try to get a permit. Your permit will almost certainly be denied, but you should ask anyways. If a permit is denied, hold the rally regardless, citing your constitutional right to free expression.
Either way, send out a press release immediately. It's an opportunity for advance publicity for the rally.
If a permit is obtained, think about obtaining a real sound system and some rock bands. If you are planning a very large event, then insurance should be considered.
Send out a press release. All local and regional media should be told of the event at least two weeks before the event. Make sure your fax press release has the date, place, time, reason for being and contact info. You should also call up sympathetic reporters to tell them personally about your event and invite them to attend. When being interviewed by the media, pick a simple theme in advance and keep repeating it.
Keep it peaceful. Make an announcement at the beginning of the rally let everyone there know that we are not there to hurt anyone, not break anything, but to just make a whole lot of noise. That really gets the crowd going and deters provocateurs.
Plan out your parade. If there is to be a parade, have some solid folks out front, carrying a big banner. Make sure they pull it tight so people can read it. Also ensure that they walk really slowly, to keep your mob tight.
Have a well-planned route that your front banner folks all know ahead of time. Make sure your route doesn't send you head-on into oncoming traffic, that it is in a very public, high foot-traffic area, and that your route is given to the local fire department.
Give away marijuana. If you can afford it, the joints or other canna-treats can be given out.
Film the police. Have some brave people designated to follow any "harassment" cops around with cameras. The people wielding the cameras should be firm but polite with the police, and should not have any marijuana on their person. Their goal is not to enrage the police, but rather to keep them distracted and show them that they are being filmed.