Well, there are many considerations. For starters, it depends what your local and national legislation is like.
Then if you go legit, will you have to jump through all sorts of expensive hoops? e.g. to get a licence, to be able to raise funds, to be able to rehome, to be inspected by a vet etc. Do you have the expertise (or access to unlimited free advice) to handle all the kinds of reptiles that you'll be given? Can you really rehome numbers of the bigger ones that seem to be losing popularity e.g. adult iggys? Can you afford unlimited vet fees?
I have a friend here in the UK who runs a small dog rescue and it's a thankless 24x7 job that costs her a fortune and gets her nothing but hassle from all directions (ex-owners, future owners, local authority, police, other larger rescues etc). Luckily she has a sympathetic vet who keeps bills to a minimum. She does it for the love of the dogs and a deep moral conviction that this is necessary to prevent their suffering. With the other 6 people in the organisation, she rehomed over 800 dogs in 2004 (as a matter of interest, that's about the same as PETA managed for the whole of the USA).
In your place, I'd stick to doing ad hoc "good deeds". You could be opening a real can of worms making it official, unless you're so motivated that you intend to make the rescue your life's work and pour all your spare cash into doing it.
Sorry to throw such a downer at you but having watched my friend being run into the ground over the last 20 years, you really need to know what you're getting yourself into.
Good luck, whatever you decide.