If you find a bug, label it with the "bugs" tag, as well as the "security" tag if the bug relates to security. Then, be sure to label it based on the bug report template.
Questions are things that you are unsure about. When in doubt, mark it as a question, though be sure to always answer it yourself before posting. Be sure to format the enhancement as dicated in the feature request template, though be sure to always answer it yourself before posting.
Pull requests are when you want to change the code yourself. Please link to any relavent issues by clicking on the gear next to "linked issues".
Additionally, add this to the milestone the issues are linked to, and label it based on what you are trying to solve (Bug or Enhancement and what type if necessary).