You could correspond with the moon phase and day of the week while writing your spell. Day of the week would be Friday and moon phase could be waxing, full moon or even new moon since it marks new beginnings. If you can get a hold of the taglock of your best friend, it could be incorporated in the spell. Taglock is basically a picture, nail clipping etc of that person. You can use an orange candle for friendship spells. You can carve your name and your best friend's on the candle, charge your candle with your intention before starting the spell. You can roll your candle in herbs related to friendship and reconciliation.
I'm just giving a vague idea about how you can use these ideas in whatever steps you have in your spell.
You could also try to gain some contact with him/her, magick isn't a solution of everything. Try sorting things out with that person, maybe it could turn out that you didn't actually needed a spell!!! Communication is very powerful
I hope this answered your question
And good luck with your spell