First and foremost, a good melody dictates so much emotion. While this isn't the sole factor, it can certainly limit the emotional extend of your piece. An example of how melody conveys emotion may be found, for instance, in Cohen's/Buckley's "Hallelujah". Of course, this is very specific, and very linear; it may come off as clichéd.

Also, to me, the most noticeable clichés generally occur in the melody and progression. It's up to you to get creative here and avoid this!

Sometimes, tweaks to dissonance can vastly expand the emotional impacts of music. To really "draw out" emotion through tensive dissonance, you may try to extend suspensions across extra measures, hold on to unresolved cadences, and perhaps play with dynamics around those spots. In this way, you can effectively extend the tension and thus create a more gradual, perhaps more dramatic rise to the climax and fall therefrom.

Finally, tempo can certainly affect emotion. A faster tempo, in most styles of music, creates a more energetic feel. A slower tempo may be used to convey softer, less energetic feeling.

So, to recap, besides focusing on the general melody, I would try to focus on unresolved cadences, gradually play with dynamics, and decide on a tempo early on. Be creative!!!