"I have very good relative pitch, I can play any melody I hear and am able to improvise all day long.
But, when trying to come up with a new melody, I usually either:
- can't get existing songs out of my head, and end up playing them instead of making anything new, or
- the opposite: try too hard to avoid anything familiar and end up with complicated, non-memorable melodies.
Am I just lacking inspiration, or can I make any practical change in playing which would increase chance of stumbling upon an interesting melody?"
2. WRITE WHAT YOU FEEL. This is what makes your music unique; the way you yourself deal with the emotions behind your music...everyone handles emotional impact in a different way. In every case, the way a composer or songwriter expresses their emotion through their work shows the listener who they are. Speaking of which...
3. FIND SOMEONE TO LISTEN. Anyone. Composers have to find a happy medium between writing purely for themselves and for public consumption. An audience, whether they are friends, family, experts, non-musicians, etc., will easily give you feedback on what they hear. A more diverse audience means more diverse feedback as well!
4. KEEP WRITING! As soon as you have a new idea, repeat these steps! Who knows? You might discover something that fits in your piece or you might decide to write a new one based around that idea! It's all up to you! All of these steps can be accompanied by studies in theory, form, arranging, and orchestration; these tools will help you on your journey to wherever your mind takes you! Have fun!