A lot of people just starting out on the Wiccan path (or other spiritual path that uses altars or shrines) get this book or that one and start obsessing over following the directions in it exactly - finding the perfect items for rituals and their altar. But what they often fail to realize is that the most powerful altar is one the means the most to you - altars are very personal objects so don't worry if you can't or don't want to follow directions in some book. Do what feels right to you.
What is an Altar?
An altar is really just a working space set with objects that reflect you, the purpose of the altar, or the ritual or season you are celebrating at it. There are many types of altars - an ancestral altar, meditation altar, or moon phase altar are all great supplements to your main, working, ritual altar. Perhaps you will want to create your ritual altar fresh every time you need it (practical if you don't want everyone in your house to know what you are practicing) instead of being set up permanently. Decide what the main focus of your altar will be (and don't be afraid to change it as your practice evolves).
Before you go hunting for all those items you want to buy for your altar, relax! First decide the best location for your altar. It should be one that is relatively "safe" - meaning a place that isn't in the main traffic zone of your home where it might be bumped or disturbed (or become a place to dump mail or keys) or where your children or pets will think its the perfect spot to play. If you have a spare bedroom or unused space you can use, awesome but even a small closet or a corner of a room can work well. Need to keep it away from children or pets? A wall shelf can work wonderfully! And remember, you can have more than one altar depending on your path and what you want to use them for.
How to Create an Altar
Once you find a place and decide the purpose of your altar, start with a simple altar cloth - measure the flat surface you are planning to use and take a trip to the fabric store. You can often find remnants of very beautiful fabrics for just a dollar or two. Get some fabric paints, beads, feathers - whatever you like and decorate it if you want. Get several fabrics of different colors if you want to set up a seasonal altar. Let your intuition guide you and have some fun with it - your altar doesn't have to be serious!
Now that you have a cloth, most altars have one item for each of the elements of the Craft - Earth, Fire, Air, Water and Spirit and is usually referred to as an Elemental or Basic Altar.
Look around for things you already have that mean something special to you - they will already have great energy. Traditionally a chalice or cup is used for water, but perhaps your grandmother's candy bowl is perfect or that beautiful sea shell you found on your trip last summer could represent water. Small fountains are also perfect adding the beautiful sound of water to your rituals. Candles are wonderful, but not always practical depending on where you set up your altar or if you have cats that can knock them over (one of my cats set herself on fire by brushing against my candle at the wrong time - I freaked more than she did and she only singed a few hairs thankfully). Perhaps a night light or electric Christmas candle would be a better fit for fire for you or the more traditional witches dagger known as an Athame - or even a photo or painting of flames. Air is usually represented by incense or a wand, but a feather found on a spring walk would do as well, especially if you cannot have the smoke incense create. A pretty potted plant or found rock or pine cone works as well for Earth as the traditional pentacle. Spirit could be represented by a candle, a pentacle (how about one made from twigs from the nearby park!), or any image of a God or Goddess that you like. Don't feel like you have to stay traditional or use tools that may not feel comfortable to you. The more personal the items you use, the more personal the energy of your altar.
Altars also often contain a sacred statue representing your patron diety or statues of both your favorite God and Goddess. Don't stress out though if you haven't decided on the form of God/dess you prefer yet - just go with a more generic symbol of spirit such as a pentacle or one black stone for God Energy, one white stone for Goddess Energy. Add flowers or other seasonal touches as offerings if you'd like.
The altar in my office (right) has changed many times over the years, but is always a point of peace and calm to me. Turning on the fountain and lighting the candle every morning centers me and lets me focus better. It is filled with things I love.
Beyond the basics, add special objects depending on the purpose of your altar.
Ancestral altars are great to make and pretty easy - photos or mementos of members of your family in pretty frames with a candle or offering dish is all you need. I have a lovely wooden box on mine (which sits on a table that once belonged to a great Aunt) that I use as a memory box. On the birthday or another special date of the person that has crossed over, I sit down and write out one of my favorite memories of them or find a photo or make something that reminds me of them adding it to the box. On Samhain, I read thru those I've written in the past year remembering each person in turn.
Moon altars can have any shiny, round object to represent the moon such as a silver tray. For years I have used a silver blown glass Christmas ornament with the hook and cap removed sitting in a tapered crystal vase - I cover it with a black cloth completely during the dark of the moon, partially for other phases and let it shine uncovered during full moons. It currently sits on the window sill of my temple room absorbing the energies of the moon.
Meditation altars can have anything that helps you focus - a statue, incense, candle or mirror are some ideas. A metronome that musicians use to keep the beat, a fountain, or small mp3 player could all be used to help you get into the meditative state. These altars can also do double duty for divination being the place you spread your runes or tarot cards for a reading or the place you journal after meditation and rituals.
Creating an Altar for Spells and Rituals
If setting an altar for a specific ritual or spell, again take a look around and figure out what represents the purpose of the ritual best to you - it will automatically be more powerful and just the process of considering objects and designing your altar can be magical. If you are not going to let the altar set up permanently, find a pretty box to store everything in when not in use. Craft stores have inexpensive plain wood boxes of all sizes you can get and paint or decorate as you'd like. Perhaps you'll want to get several and store seasonal altars in their own boxes for when you need them. This would also make them portable if you want to practice while on a trip or in a local park instead of at home.
Spell altars should focus entirely on the purpose of the spell so take the time to consider correspondences of color, candles, oils, herbs and anything else you want to use. Set up the basic Elemental altar first to balance the energies of it and then add whatever you will need for your spell or items you want to charge or cleanse.
Keeping A Secret Altar
Do you want to set up an altar where others don't appreciate or don't follow your beliefs? Keep it simple and secret. For years I kept a potted plant in a large dish on my desk at work to represent Earth and a small fountain to represent Water. Around the base of the plant I had stones for each of the other elements and tiny statues (fantasy gaming type) from a hobby store I painted by hand to represent the God and Goddess. No one but me knew what it truly meant, but I found it very centering and calming even during the most stressful days. I know someone that has created an altar charm bracelet with charms and stones on it that represent the elements and God/dess to her. She wears it every day and always has her altar with her! Prayer beads or malas can serve a similar function bringing your focus back to your spirituality whenever you need it.
Books are wonderful, especially when just starting out, but don't get too bogged down in what they say you "should" do - treat them as guidelines and let your own intuition be your true guide. Don't be afraid to mix things up and change them from time to time either. Enjoy the process and your magic will be that much more special.