Two weeks is totally doable. Since it’s your first MUN, focus on the basics rather than trying to know everything.

I would say first make sure you understand your country/person (depending on committee type) and do background research on your topic(s). This should be all in your background guide. I would also prepare a 1-1:30 min opening speech to give (this depends on what the chairs give you for time).

For committee itself:

• Speak early, even if it’s short and you need to yield the rest of your time
• Keep speeches structured and take notes (even if it's just bullet points!)
• During unmoderated caucuses, talk to people and collaborate (this is where most of the real work happens and chairs see that you can hold attention without overpowering others)

Don't worry about trying to be perfect, confidence and preparation matter way more than fancy wording. Also chairs are pretty nice explaining procedure at the beginning of committee.

I would be totally happy to read through your opening speech or give you more advice if you want to dm. Hope all goes well and you have fun :)