This is to be the first post in my "Polytheism 101" series. As the title says, it will cover the basics of putting a shrine together. I feel I should also note that though this series will be called "Polytheism 101," the ideas and methods shared here can be applied to just about any Pagan path.
How you decorate a shrine is largely a personal matter. Your own taste, which tradition you follow, and which gods you honor - if any in particular - will determine what exactly your shrine ends up looking like. Big or small, extravagant or simple, the sky's the limit. So my focus here will be about the various items that are used for ritual and devotional purposes.
Items that are commonly used for a shrine are a pitcher and bowl for libations, a small dish and cup for food offerings, an incense holder, a candle holder, a bell (or a sistrum or drum), and a deity image or religious symbol. I set up these items as an example in the following picture:
I set up this sample shrine on an empty spot on my dresser. For your own shrine, any such clear surface will do, but I do prefer my shrines to have an entire surface all to themselves (such as on a shelf) to ensure that any clutter doesn't encroach on the shrine space. As for items, for my libation bowl and pitcher, I used a cruet that I bought at a supermarket for $3, and an onyx bowl that was given to me as a gift. For an offering dish, I just re-purposed a saucer from my cupboards. The tea light candle holder and "incense holder" (it's just a pretty dish I liked and put one of those Morning Star incense tiles in it) were purchased at a craft store for $1 each. The offering glass was a thrift store find for about a dollar, and as you can see, the deity image is just a picture of Wesir that I printed from my computer. My splurge item is the bell, which I got at a local metaphysical shop for about $6 or $7. The reason I'm explaining where I acquired everything and for how much is to demonstrate that a shrine can be assembled easily and for little cost.
I remember that as a young pagan, I would often read about all of the things one "needed" in order to practice a certain path or tradition successfully, and feel overwhelmed by them. Such lists (especially those for more Pagan/Wiccan leaning practices) are often quite long, and the task of acquiring so many things can be very daunting to anyone who is practicing casually or in secret, or who has a limited working space or tight budget. Yet the more experienced I became, the more practicality became my rule of thumb. You don't need a wand, special robes, or crystals. Even an athame can be left by the wayside when you have a perfectly good index finger to direct energy.
Even my list, as short as it is, shouldn't be seen as a list of requirements that you absolutely need to be a decent polytheist. The items on this list are the things that have proven to be the most used in my own years of experience. But if you feel that you would rather offer a glass of water instead of making a libation, then obviously you can forgo the pitcher and bowl. If you would rather clap your hands or use your voice, then you can skip the bell. Even the deity image/symbol isn't a necessity, as not everyone finds visual foci useful.
You can see more examples of shrines in my post about 'Anatu and Athtartu, and in last year's posts about Wep Ronpet and the Day of Chewing Onions for Bast. There is also the website Shrine Beautiful, which features shrines, both simple and ornate, from many different paths.
Other posts in the Polytheism 101 series include "Offerings" and "Ritual."