Adding the heat: Amounts are up to you, but start small, because you can’t go back. Hot sauce is the easiest to manage — start with a dash, and go on from there. About 1/4 of a very finely chopped fresh jalapeno (de-seeded and de-veined) per avocado is a good place to start. 1/2 tsp finely minced canned chipotle in adobo is a good beginning. Any combination of the foregoing are fine, and there are other options — canned green chiles and chili powder come to mind. Guacamole is not meant to set you on fire, so be gentle.