@renniekas you asked the right person. I'm an Apollo devotee.
My advice is finding something the reminds you of them that you can always carry around. For me, I do a ring with a yellow jewel.
And then, whenever you eat or do something, quietly say something along the lines of "I dedicate this cracker to Apollo" (the cracker thing is a joke that I have. Aka: "Pollo want a cracker?" That joke actually was what started my whole devotee work to him, lol)
If you can make an alter, great! If you can't, that's alright! My alters are literally just a book shelf and a bedside drawer.
If you can make an alter, I recommend putting something to represent the god the alter is dedicated to in the middle. For example, on my alter dedicated to Persephone and Hades, I have dead flowers.
I then recommend finding a crystal to put on your alter that reminds you of the god it's for. For me, the crystal that represents Aphrodite on my group alter is a amethyst in the shape of a heart.
If you have candles, put one on there. If you have colored candles, even better! For Aphrodite, do pink and red candles. For Apollo, do orange and yellow.
I also recommend researching the symbols of Aphrodite and Apollo. While I can't remember Aphrodite's, I do know that Apollo's symbol is a circle with a dot in the middle, along with the sun ofc.
And here's another little tip that I do in general as both a witch and a devotee: Every morning, when you go outside, say "good morning" or "good morning everyone." Then, if you see something that reminds you of your deities, like the sun for Apollo or a seashell for Aphrodite, say "good morning, Apollo/Aphrodite."
I can personally hear Apollo, but I do know that's not always the case for other deities and devotees.
Anddd that's all my advice!