She is traditionally honoured with an idol, a representation of some kind, so finding an image of her online that you like is a good start, the Egyptians valued standardised art and would have probably loved to be able to print things. 
Also, do some reading about her many qualities, this is a good starting place:
The first image on that page would be perfectly suitable, it;s very traditional and seen by thousands of people.
Once you have that, make her a small alter, to the west, and offer her a candle or tealight, and some water in a clean bowl or cup, she also enjoys flowers and perfume, and incense.
There’s not a specific ritual for this except to focus on her image and ask her to be present in your life, to communicate with you in ways you can understand, and then speak to her from the heart about the things you would like her help with, you can do this out loud, or silently in your mind.
Hathor is a goddess, not a demon or angel, so afaik she doesn;t have an enn.
Sigils are similarly more associated with angels and demons, but there is an intriguing new method posted here that may help:
She likes turquoise and teal, gold, rich reds and other gem colours, as well as gold, and for incense, frankincense and sandalwood, and rose.
Be honest and also respectful, she sees what’s in your heart so there is no need to try to fake anything or put on a mask but at the same time, she is one of the oldest goddesses we know of and is immensely wise and powerful.
I was literally typing this and checking what I had on my desktop when you replied again. 