Everybody gets a little nervous sometimes when they try to be affectionate with their love one in 
the school environment. After all, it’s not exactly the most romantic of places, its purpose is the business of study, not love, and besides that, your mates are looking on most of the time – hardly conducive to fond lovey-dovey behavior. Let the ideas here help you beyond the initial nerves and sick-feelings so that you can behave in an appropriate manner with your girl at school.
Leave little notes in his/her locker
If this is your boyfriend and he shares his locker with someone else, than this is not such a good idea. If his buddy finds the mushy letter before he does, your boyfriend will never hear the end of it. By the way, you don’t need his locker combination, just slip the note between the cracks of the door. what to write on a love note.
Treat him to his/her favorite snack
You could also bring him a bag of his favorite chips or candy, or his favorite chocolate bar. If you go with a chocolate bar, unwrap the wrapper carefully before giving it to him and write a love note on the inside of the wrapper. Then fold it back up and as long as he opens the bar carefully he will see your note.
Write a love note in her notebook
If you can get your hands on one of her notebooks secretly write little messages for her throughout it. She will find them when studying and taking notes in class. Girls love this. what to write on a love note.
Create a secret “I love you” code
Create a secret code that means “I love you”. Ideally this is a hand gesture, such as rubbing your nose or tapping your forehead. Use this to say those three magic words anytime…including in front of his friends. It will be your little secret.
Be a gentleman at all times
Open the door for her, help her carry her books, step aside and let her walk through doorways first, walk her to class and/or home after school, let her order her lunch before you at the cafeteria, get her more ketchup or napkins if you see that she needs some, hold her hand while walking together.
Spend lunch alone together
Spend some of your lunch breaks alone together, go for a walk outside, find a private place in the park to sit and talk and eat your food.
Try this little trick that a friend of mine did with her high school sweetheart: make plans to both ask to be excused from class at a certain time (works only if you are in different classes). Have a private meeting place arranged and go there to exchange some sweet kisses before dashing back to class.
Use the phone to be romantic
If you are able to talk on the phone blow kisses to each other by giving the receiver a quick “peck”. Or, call her just to say goodnight. Or, watch the sunrise/sunset/eclipse together while talking on the phone.