It's up to you where you'd like your children's pictures taken. I've never had any problems finding at least a few places in a house or garden that I find suitable but if you prefer, we can meet in a park or wherever you fancy.
First I have a look around; while I'm doing that I talk to the kids and try and get them involved. They show me their toys and where their favourite place to sit is. This makes it a bit easier to get pictures of them later on because they feel involved in the decision making and I know a little about their personalities.
I take a few pictures and then move on and take more in a different place so they don't get restless and start doing creepy fake smiles. Sometimes they just don't want to keep still or even look at me but that's totally normal. We might have to take a break and play lego but we'll try again later and I stay until I have the pictures I think you'd be happy with.
I cart around a 'baby poser' which is basically two U shaped bean bags and a bean bag sausage that fit together to prop up new borns and babies who are a little unsteady sitting up on their own. Some babies love it, it hugs them a bit so they feel secure but some freak out; as you can see in the photos below.
If they don't want to sit in the baby poser, they can be held or we look around for other solutions. I really like the ones with parents holding them, it shows how tiny they are and you get really sweet expressions on their faces.
When we've finished taking the pictures, I go through them, you receive an online gallery and can decide which prints you'd like included in your package.