1. Don't get pregnant. If you are unsure in the least how to ensure this result, STOP, and research various ways. (Not having sex is one very reliable way, but works against your stated goal.)
2. Make sure #1 is addressed in a reliable manner.
3. Did you take care of #1? If not, stop and go back.
4. Ok then. Start with, oh, kissing, or a light snack plate which you feed to each other. Likely your partner is clueless too, so only do what you both want to. Explore, have fun, don't set an agenda (except for #1, which is important). People tend to figure out this sort of thing on a daily basis, and have for millennia. Communicate with your partner such basic information as "that's good", "no, stop", or even "how about you do this" if he's being annoyingly hesitant. If you've never before seen a live, semi-naked or naked, probably aroused human body this up close and personal, relax and remember that field research is one of life's best learning methods.
5. Remember #1. When employing your solution to #1, explain very clearly to your partner that, unless #1 happens, nothing else does. This is important. Don't skip this part.
6. If you have a "this is the big night" mentally marked on your calendar, shower before meeting up, and wear what you consider to be an alluring outfit, at all layers. If all your groceries are going to be unloaded, make sure he's taking them out of attractive packaging. Likely you'll both enjoy this part.
7. #1 is a dealbreaker. Remember #1.