This is a heated subject for many. In my personal opinion a good DJ plays both songs he likes and the audience likes. That is where the "Skill" comes in. Picking the next song to play based on how the audience is responding. When looking for tracks I literally just troll the internet for hours. Good places to look are obviously hype machine and the charts on beatport. Also listening to podcasts from big name DJs like Tiesto is a good way. In short listen to A LOT of music and think about how you and other people will respond to the selected track. Try to get a varied selection of music. Even if you are only playing Trance you can switch between some psy, vocal, 130 bpm, and 140+ bpm types. You want your set to flow but not sound repetitive.
On a side note I just moved away from Orl in November. Man do I miss BBQ bar. Punch the DJ at sky 60 for me when you get a chance. Dude sucks.