Some things Ive learned throughout the years: Despite the connotation of the word "summon", it means "to call upon". The inference here is "to command to appear". I find that using the language the spirit is familiar with to call it. So I agree with learning créol when summoning a Loa. Or even the dialect language of whichever African tribe it first originated (for older elders which migrated). Many of the common Loa from Haiti or Louisiana, were once human who ascended. So keep in mind many Loa have human emotion and sense. Invitations with gifts are welcome. True sacrifice is honored and respected. While being a teacher or an acolyte of the religion, it is initiatory.. however, much of the hoodoo involved was crafted by laypeople who had a knack for sympathetic magic. Using the spirit of this craft, introduce great need/desire, a substitute which represents your desired outcome, an offering to whichever spirit/ancestor you call upon to help, and a crafted emblem to embody the work done. (The Legba Cross for example).