Make Offerings
King Paimon has always been a humble and accepting spirit in personal experiences. Offerings, whether they be great or small, have always been accepted and appreciated by him. If you are able to offer specifics though, you can't go wrong with:
Flowers - Sunflowers, roses, jasmine, lotuses, lilies, daisies, blue bells, marigolds etc. have always been on my list of preferences where able as these are personal associations according to unverified personal gnosis.
Food - Baked treats, sweets, breads, meats, vegetarian meals, fruits, and spicy foods seem to go famously with King Paimon. Rose and vanilla flavour essences also went very well. Beers, wines, whiskeys, and plain water was enjoyed when offered. Simply set it on another plate (or make room on one plate to set aside your offering if you have to) and enjoy your piece as well. Warm drinks such as sweet coffees are nice, and teas such as chai tea, jasmine green tea, and hibiscus teas amongst others. You'll definitely find something that works.
Incense and scents to offer - Frankincense, vanilla, sweet amber, patchouli, jasmine, rose, lotus, lily, even mullein. Scented candles and oils also work terrifically. Sometimes grabbing some cloves and pushing them into tealight wax, not too close to the wick, can be comforting for me. Clove may not be the first herb that comes to mind (maybe not for anyone else, honestly), but its an idea to utilize for allowing scent to rise and fill a space in offering to King Paimon. Just be careful not to set your house on fire by doing this.
Artistic pieces - A spirit entwined with the arts is bound enjoy artistic pieces. Sketches, paintings, poetry, short stories, writing music, and even the sound of a ringing bell can be an offering through sense of hearing and feeling through vibration. Creating drawings of camels, crowns, bells, flowers, and even the sun can also be a method for those unable to openly display offerings. What you personally associate with King Paimon is best.
(This is not by no means exhaustive or exclusive to King Paimon. Spirits share attributes, associations, and more all the time! And what works for me may not work for you as it is heavily UPG)
Involve him in daily activities
Going to the shop? Consider keeping King Paimon in mind while shopping, or invoke him before making the journey. Reading, meditating, drawing, writing music, and even coding - ask for King Paimon's presence or keep him in your thoughts while pursuing goals or engaging in tasks. It can even be as simple as while cleaning the dishes or listening to music. Enjoy dancing? So does King Paimon. Like listening to music? You've already guessed it. King Paimon's elemental associations vary practitioner to practitioner, so if you associate water with this divinity and have access to running water and can take five? Relax to the sounds and connect with this element. Does air resonate more? Connect with the wind as it brushes across your skin, feel its cooling/warming touch and know that King Paimon is there with you.
Meditation
This ranks amongst one of my favourite. Direct invocation through meditation, allowing communication. It can be planned or on the spot if you've got the time and are able to do this. Pathworking is also a method of creating contact while in a resting position. Most practitioners who already work with spirits will have some form of meditation they prefer.
Spreading his name
Obviously, this also plays into offerings. A lot of entities enjoy having their name spread around and known by others - King Paimon is one of these spirits. Making art and digitizing it, or making digital works also act a pathway to making this divinity's name known.
Acts of self-improvement
Demons like it when we take care of ourselves, and actively strive to better our talents and overall lives (this includes facing our fears). Little things like taking a bath, or overcoming getting out of bed in the morning is of significance to the divine. Caring about yourself and your needs is just as important as taking care of what might be requested of spirit. The divine may even make a request for you to think of your needs more often too!
Simple Acknowledgement
Appreciating what King Paimon represents/brings with him, what he has done for you if you work with him, and any potential future workings together. As simple as it is, understanding his lessons and being thanking for them can all you need on occasion.