Use Csound to play simulated horn scales. Listen and critique. This is the most important part. Describe as clearly as you can the qualities of horn sound that are captured by your simulation, and those that are not. My own preliminary work .
Optional variations Compare different amplitude envelopes.
In particular, try more and less accurate envelopes, using more and less break points. Try wavetables taken from recorded notes at different pitches. You should do this step quickly, over the next week. Choose one period from a recording of a horn note, and find its sinusoidal components by taking a Fourier Transform. Lots of different software tools will do a Fourier Transform for you, but I found Scilab to be most convenient.