What I like to do for birthdays or new years eve is a "wheel of the year" spread. This spread doesn't require a question to begin.
Shuffle the cards good and lay out in a large circle 12 cards, one for each coming month. Start at the top with the nearest full month, since today is May 31, your top card would be June, followed by July etc...
Each card is the general reading for that month or something the sitter should work on that month.
The nice thing about this is that if someone is concerned about a card, then clarification cards can be pulled or even a whole new question asked and layed to the side about that months card.
I like this spread for sitters that don't have a specific question or are just wanting an overview of the year.
For a newbie it is also good because a lot of times you don't have to weave the cards together into a story since it's basically a one-card reading for each month. It can also be compressed down by doing a 3 or 6 month "wheel".
I'd start with this one because it gives an overview of her coming year until her next birthday and might spark more questions to ask later. Don't forget to journal it and give a copy to your sister so she can refer back to it through the year and see how your reading is panning out or what obstacles she might be facing in the next month.