How do I prepare for a GA committee?

Read the background guide and conference guide. Each committee will publish a background guide that will have information about the topic, rules of procedure, and guidelines for writing position papers. If you cannot find rules of procedure or position paper guidelines in the committee's background guide, check out their website or conference guide.

Do some research. Make sure you address all of the research starting points.

Break down the topic into subtopics. During committee, each country will have a different aspect they want to address. By breaking up the main topic into subtopics, you can preempt what will be discussed during mods and do some extra research. 

Brainstorm solutions. One of the biggest parts of MUN is debating solutions and combining these ideas to make resolutions. As such, you want to brainstorm solutions that your country would support. One of the easiest ways to do this is to figure out which subtopics your country supports the most and then brainstorm solutions for those subtopics.

Write your position paper.  Your position paper is essentially a culmination of the relevant information you have learned and the solutions you have created. It'll be very useful for making speeches and understanding your country's perspective.

Write your opening speech. Your opening speech shows the other delegates the perspective of your country and makes it easier to find allies. If possible, try to memorize it before the conference. If you run out of time to write your speech, you can always use sections of your position paper. 

Read the conference policies. Every conference has specific policies around technology, dress code, and pre-writing resolutions. Their list of policies is usually somewhere on their website, so take a look so you know what you can bring into committee and prepare accordingly.

Prepare your research binder. Make sure you put all of the necessary documents and information in your background guide. This will be all of the information you have access to during committee so ensure that it is concise and relevant.

Practice writing resolutions. Resolutions have a weird format that takes some getting used to so it's recommended that you take some time to practice before committee; this will give you a leg up on other delegates and make it easier to infiltrate blocs.