Add some vocals to your set. With a microphone you can easily add flavor to a mix. You can use the vocals to transition to another track, with a small paus between the songs you can drop the vocal just before the next song comes in. Most DJ-mixers have a microphone input. But make sure not to overdrive the microphone when speaking, or the sound might go into cheap karaoke style.
There are useful techniques when speaking into a microphone by holding your thumb inbetwen the microphone membrane and your mouth, this is to reduce the "pop" sound or just by turning the mic at a 45 degree angle. Using these techniques will make your vocals sound cleaner.
Have a notepad with some words are maybe rhymes written on it, just to know what to say when you want to drop the vocals. If mixing and speaking is not possible at the same time, then wait until after you transitioned the track into the other, the intro to the next track is often not as busy as a Chorus section. Also do speak over the mic to much, on lets say after each track, give it some room and leave every other track without vocals. Just a Word here and there is cool. Something like: you're listening to.... and then maybe your dj name and and the name of the song your playing or the songs you played after the last vocal drop. Like a radio DJ.