Every time you get a new project, no matter how big or small, there are certain things you need to be clear on above and beyond the creative brief.
Sometimes, you won't get an official briefing (someone may just stop by your desk and say "Hey, we need you to do some print ads for Thursday!") so grab your notebook and try to find answers to the following:
Questions to ask (some out loud and some to yourself):
WHO: Who is the brand? Who is the target? Who are the other people on the project? Who do I need to show my work to? Who is the person on the client side we are presenting to? Who is presenting? (Sometimes you do the work and someone above you takes it to the client.)
WHAT: What is this project trying to accomplish? What is the brand selling? What are the deliverables (What are we actually creating? Banners? Print ads? TV scripts?) What are the mandatories (things my executions have to include)? What are the things the client hates?
WHEN: When is the internal presentation? When is the client presentation? When is this ad/campaign launching?
WHERE: Where will this campaign be running? Where are the internal and client presentations? Where can I find additional information on the brand, the target, the medium this campaign is running in, the competition, other campaigns like this, etc?
WHY: Why are this medium? Why this message? Why this time frame?
HOW: How should do you want me to share my ideas? (Marker comps? Full layouts?) How can I add something extra to this project? How can I go above and beyond? How can I best show my skills? How many ideas/executions should I bring to the table?
Ask as many questions as you need to make sure you're clear on what is expected.
If you're embarrassed or shy, ask someone you're comfortable with after the meeting in private, or send a follow up email with your questions.
The more information you have, the better you and your work will be.
The only stupid question is the one you didn't ask. It's better to ask now and know, than to do the wrong thing later or worst yet, do nothing because you're not sure.
Get to work!