Step1
For the songs you know you will need to specifically select, such as your first dance, mother/son, father/daughter, etc, download the songs you have selected, burn them onto a CD, and give them to the DJ in advance. Odds are, they will probably already have these songs; however this way you are assured they will
play the right VERSION as well.
Step2
For songs that play during dinner, cocktail time, and other down time, again it may be adviseable to pre-select music and supply it to the DJ in advance. The DJ, however, may have suggestions, as well as a large selection of appropriate songs, so discuss with them beforhand. Pick something that won't be prominently noticed; Jazz works well for these times, like Miles Davis' "Kind of Blue," or albums by artists like Dave Brubeck. Of course, go by your personal taste.
You should probably have more than two hours of music readily selected. This way you won't have to repeat songs, and the DJ wont be left to guess what they should play.
Step3
For specific songs that you would like to dance to as part of the receptin party, just submit a list to the DJ. Most DJs have massive song libraries, so supplying the songs on CD should not be necessary. Many DJs now have online playlists on which you can select your music.
Step4
To facilitate the DJ in selecting the rest of the songs for the night, type up a list of criteria that you would like them to follow. Be specific both about what you would like to hear as well as what you would NOT like to hear.
For example, you may list:
1. No songs containing swearing or foul language before midnight
2. No Country music.
3. No Chicken Dance.
Or, you may request
1. Lots of Michael Jackons, please.
2. Rock until midnight, then rap.
ETC.
This way, the DJ can read the crowd and select songs that they think will get people up and dancing, all while keeping your wishes in mind. If the crowd is bored with your own musical selections, allowing the DJ to spice up the night can be a lifesaver.