Create the notes that will underpin your melody. Hum different notes and think about how they will fall together. Pick out three to five notes and play with their structure and order. A memorable melody will not jump from high to low notes suddenly but will instead have closely spaced introduction notes.
Move your melody along by adding one or two notes that stretch out to high or low notes. Hum the notes and choose a higher note if you are moving toward a new verse and concluding the melody. Choose notes that are low if you are in the the middle of your melody and are trying to extend the melody by repeating parts of it..
Write a hook that works well within the context of the notes you have hummed along to. A melody that is memorable has a hook that draws the listener in. The hook repeats itself along with sprinkled in words that complement it. For example the hook in a melody can be "we will love forever" accompanied by "today, tomorrow and always."
Build upon your hook and complimentary words. Take your hook and add a line that fits within the melody but brings the listener back to the central idea. For example, "We will love forever. Today. Tomorrow. Always. We will love forever. In my heart you will stay."
Work on your songs hook by speaking the lines of the melody. Experiment with the way that it is said. For example, "We will love forever, " can be crafted to sound like "We......will love forever." or, "We.... will love for....e...ver."