Try to harmonize this exercise in 4 parts on paper. You can perfectly get away without using tonicization to C major in measure 6 or writing advanced 7th chords and their inversions (measures 5 and 7).
The only real rule here is to avoid parallel 5ths and 8ves. The rest is optional. After you have completed the exercise, play it on your instrument to see if you like it and how it can be improved.
Here is the PDF file for printing and the MIDI file for listening.