Some essentials for a guy who's hooking up or in a relationship. Some items may be applied to the general audience while some may be a more specific/technical/expensive/impractical to others. Either way, the first rule is to KNOW YOUR GIRL. One may be different from another. Here we go.

*First, the type/style of the bag. Avoid bags that are too flashy (neon colors, wild prints), too arrogant (where the brand is focused) or something that makes you look like a special snowflake. Minimalism is the key. Remember, you are advertising yourself, not the bag. I personally recommend dark-colored leather bags. Not too big to look like you're going to sell books, but not too small where you compromise the function. My criteria is that you should be able to fit a legal-sized plastic folder and still roomy for a laptop. Sleek backpacks may also work, especially if you have heavy loads or concerned with your spine and posture. If you're on a budget, laptop bags will work too. Styles may differ among your tastes. Just make sure that you won't be ashamed to use that bag in a fancy restaurant but casual enough for everyday use.

*Essential contents are as follows:

Portable umbrella. It must be thin enough to fit it in the bag but big enough for two people. It's functional for both sunny and rainy days. The weather can give you the opportunity to meet someone under a shade. In addition, watch the weather report for the day to expect what to wear and what to bring. Tissue and wet wipes. The travel-sized ones. You may use these for explosive diarrhea or wiping yourself to cool down and remove oiliness. Or you could wipe a girl's face gently with a sheet to complement her no-make-up look. Very versatile. Pen and paper. Actually, buy two pens. Used for writing her number. Another trick is putting your number in the pen while saying that you must go. Some girls find it unique. You may buy a small notebook that's a little bigger than your palm or a steno notebook. I prefer a steno notebook because it's easier to organize notes. Again, you may use it as a prop for your lines, as a medium for writing numbers, or a whole directory if you want. A sticky note could also work. It looks appealing and you could write a note with it. Who said that chivalry's dead? Effortless but meaningful. Dental and oral products. Immediately brush your teeth after eating something smelly or after smoking. Dental hygiene is a big turn on for ladies. If she's into you, she will smell the prey before eating it. Small comb and hair products. If you're hair is your asset, make sure to groom it frequently. Hand sanitizer. To remove dirt and bad smell in your hands. Or after that explosive diarrhea. Extra shirt. To feel refreshed. I usually roll or fold the shirt to fit it in my bag.

*More technical items. May be optional. In this section, you must know your girl or bring as much as you need.

Earphones. May be a pair of earbuds and a splitter. Recommended if your target is a known audiophile. Just don't give her your mixtapes just yet. Medicines. Meds such as pain relievers and antihistamines may give you a big chance to a girl in front of you in the train suffering from migraine. A little joke on the side and you've got a show. If your girlfriend has a known health condition such as dysmenorrhea, allergies, etc., it's best to carry some extra for her. Food. Chocolate bars and candy will fit in the bag for sure. You may bring some for you or for a conversation starter. Women have been known to be weakened by chocolate. Band-aids. Some women wear tight shoes and very high heels. Give her some band-aids and expect a smile (or more). Novel. Or any small book you could squeeze in. To fight boredom and to give you a sense of sophistication. Laptop/tablet. Make sure all accessories (charger, mouse) are included. You could watch episodes, play games, whatever. Just make sure it wouldn't eat up the conversation. Towel. Especially on a hot day. Offer her to put a towel on her back to help her cool down. But be careful of feminists. Deck of cards. Because why not?

Hope this helps. You could add more or compare "bag builds".