Sleepless in Seattle, etc. Magnify their faults and attributes. Most of all, make them real. Both hero and heroine must have internal and external conflicts. Create characters with built-in conflict.
Conflict can be quite simple.
Conflict is what keeps your story moving forward. Conflict must be something that causes an intolerable condition, your characters cannot ignore their conflicts. External conflicts are scenes you create that your characters react to. Internal conflicts are based on their ultimate desires and basic fear. Conflict is what keeps your characters from achieving their goals.