Stem01
Hum a single tune
Record somewhere quiet, close to the microphone. Use steady notes and leave a short gap between repeated pitches if they are meant to be separate. Start with one phrase rather than recording a complete song.
02
Check the shape of the melody
Convert the clip and make sure the highest, lowest and repeated notes match what you intended. If a quiet note disappears, record the phrase again at a steady level. Pitch slides can be represented as several shorter notes.
03
Choose a sound after export
Drag the MIDI into a track with a piano, synth or sampler. Try the melody against a chord progression, move it into another key, or trim the opening silence to place it on the beat.