Rescue Animals Ireland and Adopt A Pet are good places to start.
If you can’t find an organisation online close to you, keep in mind it’s entirely likely there are already individuals working independantly in your area who aren’t online, so it’s worth asking around. Check vets, boarding kennels and catteries, etc as people working with animals are likely to know about people rescuing them.
If you can find and join a group who’s already in business you’ll learn loads that will be useful when you do start your own organisation (having run my own business I wish I’d volunteered and/or worked in the field before I started as it would have saved me a lot of time and money). You’ll need to know about fundraising, animal health and illness, business management, rehoming, etc. And having a group of committed individuals to help is a must. It’s very easy to get burnt out, so look after yourself (and your fellow volunteers) too!!
We’ve been full on volunteering in animal welfare since 2002 and, in 2009 came to the conclusion, in the case of cats, that rescuing doesn’t make any long term difference to any creature apart from those we rescue. Every year the number of animals in distress remained the same, despite our efforts. And we realised that addressing the overpopulation problem (by Trap Neuter Return (TNR)) is a long term solution to feline suffering – if we aim to neuter every cat in West Cork, the overpopulation will be arrested, there will be fewer cats competing for resources and there will be enough homes for those that need rescued. Alley Cat Allies in the US have loads of info on TNR if you’re interested – and it’s the sort of thing an individual can get going on their own – though it’s always easier to be involved with a group of dedicated individuals!
And it’s important to set up good relations with your local vets, regardless of which approach you take. Vets fees are probably the biggest expenditure for animal welfare groups (apart from salaries, but not many charities can afford salaries in the first place).
If you’re a student, your college/university may have an animal welfare group – and, if it doesn’t, you could start one up. If there’s a veterinary department it’s worth approaching them to see if they’d support a TNR programme run by the college – there’s a few colleges in the US that do that with great success.
Hope this is useful. And good luck! Do keep in touch and let us know how you get on. And if you get a webpage for your rescue/TNR efforts, let us know and we’ll put up a link to your site. In fact, you don’t need to have a rescue centre to start a website – we started just by writing our rescuees’ stories (see this link).