The trick is to: (a) accurately assess the other person's "card", in terms of self-image, and (b) figure out what the person wants and expects from you. If he or she wants a mentor (+1) be that. If he or she wants an equal and friend (same) be that. If he or she wants a protege (-1) be that. Three points (using the 2-A card metaphor) in either direction will ruin the relationship. One exception: never go lower than a 6 or so. Also, in a group, err on the high side. If the group expects you to be the "alpha", be 1 point higher than the next highest person. If it expects and wants, someone else to be an "alpha", be 1 point lower than that person.
The "one-point" rule is important because people generally think in relative terms. If someone is extremely powerful and arrogant and acts the part (King) and you become an Ace you are "crossing" him (literally, in the number-line status metaphor). That's usually bad. On the other hand, there's no harm in being a Queen rather than an 8 or a 2. You get more respect that way. Likewise, if someone is (in terms of self-image) a 7 and you come in as a King, you're just going to be overbearing.