There are usually two structures for a comparative essay where you explore two different key ideas/themes - one that's mostly kept the same in the latter text (hypertext), and one that's been subverted by the author (although you can play around with this).
1. 1st theme: 1 body paragraph for each text, 2nd theme: 1 "synthesis" body paragraph that encompasses both texts. For this one, you want to aim for at least 3 quotes for the 1st 2 paragraphs, then 4 for the 3rd - 10+ quotes in total
2. 2 body paragraphs, one on each text, for each theme. For each paragraph, you should have at least 3 quotes - 12+ quotes in total
Remember that it's also about the quality of your analysis for each quote, and whether it actually supports your point. Each school might have different guidelines too, especially for the prelim course, so check with your teacher if you can