It’s helpful if you start with reading the first bars of a peace you are gonna play; and singing it a bit. You don’t have to sing beautifully, it’s mainly about puzzling out the rhythmic patterns without being distracted by also having to operate your instrument. Through singing, you already have the rhythm in your head and body. Now you have a bit of an idea how the piece is going to sound. If you then start playing the piece, you already know how it goes rhythmically, and you can concentrate more on which notes are in it.
If a play-along CD is included, it is also useful to listen to a few bars of the accompaniment. Then you already have heard and felt the tempo, rhythm, and style of the song.
Tip:
Also take a few seconds to look at the structure of the song (repetitions, coda, etc.), and at the fixed accidentals.