"Hello, I absolutely love your blog! I was hoping I could ask you a question. I have been having some trouble coming up with altar/shrine ideas, because I would like to have basic Hellenic components. What are the usual pieces included on these altars? Are there any types of containers or tools that I should have on there? Thanks for reading!"
Some definitions first: there is a huge difference between an altar and a shrine. An altar is one of those basic necessities within Hellenismos, and it differs from a shrine. Where an altar is a 'work space', dedicated not so much to a specific deity, but used to do the bulk of the (daily) rituals, a shrine is a devotional area where an altar might be located. In ancient Hellas, the shrine was usually a temple, the altar an actual altar, standing outside of it. Household worship took place at a multitude of shrines. Labelling something a shrine does not mean you can't sacrifice at these spots in your home. In general, you decorate a shrine but leave the altar rather bare.
Basic necessities for an altar; in ancient Hellas a sacrificial altar (called a 'bômos' (βωμός)) was outside, and either square or round, sometimes with an indentation on the top for a fire. An altar for libations or blood sacrifice could have a drain for the liquid. The indentation--or even the hole--could be used to steady an epipuron ((ἐπίπυρον), a brazier, often with either one or three feet). The materials used were often limestone or marble, stones not very resistant to heat, and thus, an epipuron was used to protect the bômos below. The epipuron was usually made of precious metals which could withstand the heat of a fire or the coals used to burn incense. Seeing as most of us don't have an altar like this, you need something to burn sacrifices in--either through a wood burning fire or denatured alcohol. So this is the first (and really only) thing you need: an offering bowl. If you burn wood, incense--a standard offering--can be tossed straight into the flames, if you burn your offerings another way, use an incense burner. That's it. That is all you need on your altar.
There are a few more basics: khernips in a vessel, barley groats in a vessel, and wine in a vessel. You also need some way to light a fire, perhaps a vessel to store the remnants of your sacrifice until the Deipnon, and of course you need something to sacrifice, including incense.
As for decorating your shrine: delve into mythology and go as wild as you want. In general, a light source and an offering bowl are staples, the rest is up to you. For Poseidon, the great Olympian God of the sea, rivers, flood and drought, earthquakes, and horses, you might look for the trident that is His symbol, appeased with fumigations of myrrh incense and the outpour of (sea) water. You could add images or statues of horses, Himself, and perhaps His wife Amphitrite to your shrine, and add seashells and anything else you can collect off of a beach for decoration. For Athena, I think owls would be a staple, Her weapon is the spear, anything with olives (including an olive tree) would be fantastic, etc. Every God and Goddess has a wide variety of items that would honour them.