Mixed chilies and peppers - well, it really depends on how spicy you want the jam to be. It also depends on what type of chilies you are using. Go for all the chilies and peppers that you know. You do want to control the heat level after all. Generally, I use 3-4 types. I use the tiny green and red chilies that are normally pretty hot, I use the big red Thai chilies, Turkish type, and the Kapia. I use a ratio of 80%-20%, 80% being the spicy type and 20% the non-spicy type but you can combine these as you wish depending on individual preferences and spiciness levels and threshold.