Summarize the following:
If you're naturally a better lyricist, you might find that you're inclined to start from lyrics. However, this is tricky and is not recommended, especially if your musical training is very limited. When you start from lyrics, you need to base your melody on the natural rhythm of the words and that can be very difficult, especially for a beginner. However, if you want to, you can start with lyrics. It seems kind of silly but many of the best melodies were born from someone just hitting random notes on a piano. If you have an instrument that you can mess around on, try this. Just play around, making patterns or just jumping around until you find something that sounds good. If you don't have an instrument, you can sing or use an online instrument. You can find many free pianos on websites and on apps available for your mobile device. You can take a really simple idea for a melody, just a progression of three or four notes, and transform that nugget of an idea into an entire melody. For example, take a small group of notes that you found using the playing around from the previous step. Think about where you feel the melody should go from there. People who are naturally musically-inclined will often just come up with little bits of music like this, like how an artist might get an idea for a painting. If this describes you, keep a digital voice recorder or a notebook (if you know any kind of music notation) If you're used to making chords, you can find a melody by playing around with chords as well. This is common for people who play piano or guitar, since those instruments rely heavily on chords. Do the same sort of playing around that we talked about in Step 1, but with chords, until you find something that sounds good to you.  You can find websites that play chords for you if you don't have an instrument to work with or you don't know a lot of chords. Try humming along to the chords and mess around with ways to make it more complex. Since you can only make one sound at a time, you'll find you have a melody before you know it. Don't worry about lyrics right away: professional musicians almost always write a melody first and use nonsense sounds in place of words. Stealing someone's song sounds like a pretty bad idea, but like taking a transplant to grow your own garden bed, you can take the tiniest sliver from another song and transform it into something completely different. If you take only a progression of four or so notes and make enough changes, then your music is still perfectly original. Just remember that you're making it into something completely different. A good exercise is to borrow from a different genre of music. Say you want to write a folk song, for example. Try borrowing from rap. Want to write a country song? Borrow from classical. A motif is a set of notes that form a musical "idea". Many songs take a motif and then repeat that set of notes, with small changes, in order to create the melody. If you're struggling to come up with a melody, this is a great fallback option since you only need to start with a handful of notes. One of the best examples of this is the allegro con brio from Beethoven's Symphony No. 5. He took just a basic motif and repeated it over and over again and created one of the most iconic pieces of music ever.

Summary:
Try not to start from lyrics. Play around! Transform a simple idea. Start from chords. Borrow from an existing melody. Build on a motif.