Start by drawing a curved line for the neck of the trumpet.
Step 2:
Add a circle for the bell of the trumpet.
Step 3:
Connect the neck and the bell with a curved line.
Step 4:
Add 3-4 more curved, horizontal lines from the base of the horn to around half the way to the base or end of the bell of the trumpet to represent pistons on that horn, which are keys that allow for variations in sound and notes with this horn.
Step 5:
Add a mouthpiece to horn by extending a small line from either side of bottom line of horizontal section of horn
Step 6:
Finish your horn off by shading your picture, leaving just a bit of shine at horn's bell and mouthpiece. Draw 4 musical notes at end of bell at end to complete drawing and create musical feeling with musical notes floating through the air at end of horn or instrument itself.