I am expecting my second baby in the next few weeks. My daughter is just under two years old. What are some ways to support her and prepare her for this new chapter in our lives?
Our oldest was two when we had our second child. Anecdotal I know, but the way it played out for us, I think that was a perfect timing to get a sibling. Before too long, they won't remember the time before they had a sibling, which is something you can't say for older children: they'll long recall that there used to be a time when they had 100% parental attention.
We read heaps and heaps of children's books on the subject. Every one we could find in the library, and there are usually whole shelves dedicated to the topic. I find that the books are often good at approaching the subject from the child's point of view.
Don't over sell the idea of a younger sibling being a playmate. That is easily a year or so away, and to a two year old, that's an unfathomable span of time. They are, from birth however, someone to cuddle with.
Include your older child in as many aspects as possible once the child arrives. Let them help. Make it clear that the young sibling is something they too have gained, even though it might not be clear to the toddler why they should be happy about it. Perhaps a doll might be helpful, that your toddler can nurse when you are nursing the infant, etc.
Make sure visitors pay attention to the older sibling first. If the toddler gets to proudly show the visitors their baby sibling, that's much preferable to having relatives who used to pay attention only to them, now walking past them to see the baby. The baby can wait. It is much more important to the older sibling than to the baby how the first visits land.
We got some advice that worked very well for us.
Little Sister was born when Big Brother was 22 months old.
We didn't try much to prepare Big Brother, because it's all too strange for a two(ish)-year-old. We told him that Mummy was going to have another baby, and a few other things, but we made no big effort to go into details. Instead, we tried to make the transition as positive as we could.
When we brought the toddler to the hospital to visit Mum, we let the toddler "discover" the baby. Baby Sister was snoozing in a basinet next to mum's bed, so when Big Brother was sitting on the bed with Mum, he looked over and saw her. Lots of happy noises from the parents about how amazing his discovery was, etc.
We had wrapped up a gift "from his new baby sister" for him (a small toy) and had placed it in Baby Sisters basinet (down past her feet, natch, nowhere she could bump into it). "Oh, this must be for you. [reads label] Yes, it's for you, from her, how nice of her..."
We got lucky. Big Brother's instincts kicked in, and he adored her from the start.
After you all get back home, @dxh's advice is all excellent.
A method that worked very well for us (older brother was 27 months when younger sister was born) is to encourage the older brother to teach his sister how to do things.
And then whenever the little sister did something new, we expressed our happiness for this and gave him some of the credit for teaching her. We did this for simple actions such as smiling, laughing, clapping and sitting up.
This method encouraged him to play with her and to spend time with her, and now, 7 years later, they are best friends and really like playing with each other (and of course they fight 25% of the time).
Note that you don't really have anything to work with for the first couple of months until the new baby is slightly more mature, so this should be combined with suggestions in other answers.
We also reduced and stopped doing this at an older age when she could understand more, so not to take credit from her achievements (around 1.5-2 years). By this time they had a pretty strong bond.
Congratulations and good luck!
Our first child was three years old when my wife got pregnant of the second child (both boys). Like with every other aspect of life, the child is very sensitive to enthusiasm. If we show enough enthusiasm for something that is going to happen, he will accept it much better. It worked very well with every stage of school experiences (starting kindergarten, beginning to eat there, to sleep there), with personal relationships, with holidays, and it worked perfectly with the arrival of the little brother.
We involved him from very early in every project we had, whether it was to choose a name or a nick name for the new baby, to buy and assemble furniture for him, to choose toys. We read books and had discussions about children's births and babies, and we made sure there always was an exciting mood when the topic was the new brother. By the time the expected delivery date was approaching, he could not wait for it, and since they met, the relationship between them could not be better.
I think the key is involve your kid in every change related to the new sibling in a positive way, without forcing them. Try to make her share your excitement. Start as soon as possible. After the birth, support the daughter's curiosity about the newborn and involve her in the baby's life, like changing the nappy and taking the bath.
Also, make sure there will be times when the daughter will do the same activities she enjoyed before the newborn arrived, alone or with a parent or a friend. The new sibling should not change everything.