I’ve heard many people say “you don’t need an altar to practice this religion!” all the time. As I delve into Hellenismos I can see more clearly how this is possible. Yet when I was getting started I didn’t really know how one could do this. Everywhere I went I saw reconstructionists talking about how to set up an altar and where and why. So I did, and I still use mine everyday; yet I see now that it’s just an expression of my faith; there are many different ways to express your faith. This is an important thing to remember when you’re pressed, by whatever reason, to hide your religion.
What we as hellenists do is worship the theoi because they deserve our worship. How exactly we do that is up to us, there are few wrong answers. Many people celebrate the Theoi in many different ways, and unless they disrespect the deity in question, it’s valid.
So, addressing the original question, how does one practice Hellenismos without an altar? The first thing that comes to mind is doing little devotional “rituals” that are untraceable and easily dismissed. For example keeping a part of a meal to “offer” the Theoi. There’s no need to feel bad about throwing it away, or in some cases having someone else eat this, it’s just meant to show your devotion. Other similar “rituals” would be a coffee “libation” before heading to school/work, meditation, or an activity specific to the deity (complimenting someone every day for Aphrodite for example).
A second method I see that’s popular is more artistic devotionals. Listening and dancing to music is a great way to connect to certain deities. Apollon is the obvious choice but really any of the Theoi can be worshiped this way. You could also draw, write (if you have the privacy, beware of paper trail), really anything you’re kinda good at. Don’t worry about making it a masterpiece at first, as the old adage goes, it’s the thought that counts.
In my opinion, as long as you do something for the Theoi as often as you can, an altar is not necessary. What is necessary is your time and devotion. That’s what really matters.