The best way to help animals is to support others who work directly with them, and to support agencies and organizations that help them, too.
Generally, the large, national organizations provide information and materials that benefit as many people as possible, such as brochures, programs and sometimes outreach activities. However, if you want to be sure your donations go directly to feeding or treating animals in need, locate a rescue shelter and donate to them. Most are non-profit groups and your donation will be deductible, if that is important to you.
It's also extremely useful and appreciated if you contact a shelter near you and ASK them exactly what they need, then provide it. Here at HiPAWS, we were lucky to have some generous people in our area who brought bags of pet food, cleaning supplies, old blankets and towels, bowls and trays, old litter boxes, cages, carriers, and even some used carpeting.