Try not to use it to separate synonyms:
“I went into the woods and saw a giant/huge toad.”
A sentence like that leaves the reader wondering:
1) What is there a difference between “giant” and “huge”?
2) If there is no great difference, why are both words needed?
3) Isn’t it the author’s job to choose the right word?
If you are signalling an alternative, remember that no space is needed before and after the slash (there are exceptions to this rule):
Jason Blake and Monika Kavalir