I think most pagans will admit that whatever idols or statues set on their altars are not, in fact, worshipped as much as representing what we worship. So we don’t worship idols; we worship what the idols represent.
Do Christians worship a cross? No. They worship what the cross symbolizes as Christ’s sacrifice for his people. Buddha statues represent the peace, love, and compassion the Buddha taught his followers.
I never put statues on my altar. I use nothing but candles, or sometimes, I use a bowl of water. It represents, for me, the Goddess, with the reflection of water symbolizes that the Goddess is me, as I am the goddess. Its also good for divining, if I feel troubled.
Other representations can include seashells, antlers or horns, plants, stones, or just about anything that holds a meaning for your. But again, people don’t worship the objects, as much as the symbol to which it represents.
What symbols do you use?