Love letters are the oldest way to show someone how much you care about them. Love letters do not need to be particularly long or short. As they say, it's all in the delivery. You should open your love letter with a fond memory, an experience you shared that truly captivated your heart. While writing, choose specific things about that day you remember. Maybe you shared a joke, or he wore a sweater you really liked, or he smiled when you spoke of something. Using these details, show him the event as it happened for you, then link that memory to how you feel today about him. Finish your love letter with "Love always" or "Yours truly" and sign your name. Now, place the love letter somewhere surprising. You could hide it beneath his pillow or in a magazine. You could even write the letter on separate pieces of paper and hide them throughout the day, leading to a final gift or surprise.
Drawing something for your boyfriend depends on what he likes. You know he likes you, but drawing something of yourself might be too vain. However, you could use a picture of you two together as inspiration for a drawing. Even better, you can draw the two of you together anywhere in the world, such as underneath the Eiffel Tower or beneath a beach sunset. Another idea, if your boyfriend is into comics of superheroes, is to draw him as a superhero. You could create an entire comic book with him as the main protagonist and you as the damsel in distress or, even better, the villain who eventually steals his heart. Laughter is the best way into someone's heart. You could also draw a portrait of your boyfriend using a picture of him.
You can combine art and words in a romantic collages. Using words that describe your boyfriend or your relationship, you can bring together photos of you and your boyfriend, his favorite things, his pets, or sports. You can draw things like hearts, holding hands, kissing lips, and other romantic symbols. Collages take on many shapes and sizes. Making a collage involves a lot of materials. You can create any kind of feeling with collages, so focus on what your boyfriend enjoys the most and use photos of you and him together along with pictures and materials from his hobbies, favorite movies or music, or romantic places that you visited in the past.