I'd firstly check the sticky thread in other spells discussion, "Designing Rituals".
My tip is this. Take time to logically define your situation. Write this down on paper. Make an evening of it - this step is very mundane, i know, no witchy, incense smoke, magic secrets here, but leave it out at your own risk. You will use the answers to help solidify your magical intent. It's also helpful to research the magical correspondences specific to your unique situation. Fortunately the internet makes this easy. Google "magical correspondences" or something like "(money, success, protection,love, etc) spell correspondences." Alternatively, you may come across a spell kit you ressonate with. Researching correspondences is important because we are doing natural magic here, thus we need all the help from our magical world as we can get.
As for an additional information about the thread. Common correspondences include: Auspicious times (for our above situation of return of a lover: morning, Fridays, Venus, Taurus); Symbols (heart, initials, doves, flowers, peace signs); Colors (pink, light blue); Herbs and Natural Items (Balm of Gilead, Violet, Rose, Lodestones); God/desses, Saints, if you so choose (Aphrodite, Hera, The Magdeline, The Holy Family, etc.); Prayers, check out Beliefnet (Peace Prayer of Saint Francis, A Love Song, by Saint Teresa of Avila); Incense (Rose, Sandalwood).
Make a list. Find correspondences for: Timing of Spell, Astrological affinities, Symbols, Colors, Herbs/Plants/Roots/Flowers, Minerals, God/desses, Saints, Prayers/Chants/Scripture, Incense.
I say simply decide what you want to include and what not. It can be a simple energy directing as well. Think about how you wish to design it and eventually you'll get to it.