Hi mummatabee,

Here are a few I like to use, If you google positive affirmations for trying to conceive you should find plenty.
One in particular I really like and so does TTC thread is "I am thinking of my Baby, I am feeling Happy Healthy and Fertile, I am imagining myself Pregnant"
There are many others, "I am ready and open to welcome my baby"
"Iam taking charge of my fertility"
"My womb is a healthy place for my baby"

As I said if you google it you should find plenty on various sites.
Good luck and it's nice that you want to do something nice for your friend.