Generally, babies, particularly newborns, have a tendency to eat or munch anything they get their hands on. This can be very hazardous or sometimes fatal if the matter is toxic.
Can someone give me some practical advice on how to prevent toddlers or newborns from putting anything near to their mouths?
You can't really prevent them from putting those things in their mouth. More than that: preventing them such thing is like preventing eyesight from adults, as at this stage the baby "feels" the world through touch and taste more than by eyesight.
The obvious solution to protect them from harm is to always make sure there isn't anything harmful around them and always keep watch and snatch anything harmful if it somehow find its way to their hand.
My two cents from own experience is to always put something safe and familiar in their reach: pacifier, favorite toy etc. Then put new things, not harmful of course, let them take it and constantly explain to them "No, this thing should not be in your mouth" for those other things. At some point they'll start to understand.
Make sure there's nothing dangerous that they can reach and put in their mouth. Other than that, don't worry about it. In fact, there is growing evidence that "eating dirt" is good for kids as it teaches their immune systems what is out there. Farm kids are also known to have a greater number of "helpful bacteria" in their systems than city kids due to a greater exposure to things.
The middle of 5 children once asked her mother how her parenting had changed from child to child. Her mother replied, "When your oldest sister swallowed a dime, I rushed her to the emergency room. When your youngest brother swallowed a nickel, I told him it was coming out of his allowance."
Shadow Wizard gives good advice. I will add tho that, more generically, you have every opportunity to control their world. You can make it small with baby gates, and filter the stuff that's in that area.
If you gate off the living room (which is usually the simplest) just make sure you don't leave normally adult things laying around... like drinks. oh yes, they'll get it. Remote, magazines, dvd cases, cigarette packs, shoes, pets, they're going to stick it all in their mouths. as long as you filtered it well, you can be reasonably certain they're not going to do any damage while not having to be horribly restrictive.
Oh btw... go get a cheap, colorful, universal remote from target. leave the batteries out and give it to them. It won't take long for them to know which is theirs.
I know this probably isn't the answer you are looking for, and perhaps I should even be asking the same question. My first 2 had no mouthing issues but my current baby puts EVERYTHING in her mouth. The best way I have found to prevent this is the good old pacifier. I see her sticking something else in her mouth and I replace it with something I am more comfortable with her having there.
One extremely common household item that toddlers can easily be exposed to, is batteries.
Make very certain that there are no accessible button cell batteries anywhere in reach. You really cannot be too cautious in that regard.
They're something that's ubiquitous in modern households, and potentially lethal for a toddler.
