Here are a couple tips to use when practicing your homework.
1) Take time to warm-up before you play.
Play a couple notes long and short, fast and slow to help get your lips loose and ready to sound your best.
2) Clap the rhythm.
When clapping the rhythm say it, (ta, ti-ti, half-note, 1-2-3-4, etc...) and clap it at the same time.
3) Go through the music and figure out all the notes.
You should be able to read the notes without writing them in but, if you have to write in the fingerings/name, erase them when you're finished practicing.
4) Play the music in "chunks."
Start by playing two or three measures at a time and then gradually add more.
5) Play the whole song.
Play the whole song at least 3 times perfectly, that way you will know you have mastered it.
Take as much time as you need in order to play the music correctly without any errors and with your best possible tone quality.
Don't forget to play along with the CD in your book! Not only does it make practicing more fun, it also helps you hear what it is supposed to sound like.