Here’s what to do:

Choose the professors in whose classes you did the best. If you had more than one class with a professor, put them on your list as well. Visit them during office hours, tell them about your grad school plans, ask them for advice about programs in your field (if they are also in your field), and ask if they feel able to write a letter of recommendation for you.

If they agree, then tell them you’ll provide them with a packet of materials that will assist them.

In the next few days, bring each one of them a resume, a copy of a personal statement you’ve written for one of your applications, and a list of classes you’ve taken in your field, when and where you took them, highlighting the ones you took with them, and describing the research you did in each class. Even better, include GRADED copies of these research papers. Also include any forms your applications require, websites for submission of letters, or addresses to which the letters should be sent, including due dates.

That’ll do it.

Best wishes to you!