New players are a joy and wonder to have in your game. They are a necessary thing for the hobby to grow, and can breathe a whole new life into your game. However, they also present some challenges to your game that as the GM you should be aware of. This is especially true during any set piece moments, particularly those that focus on the new person's character.
Assign A System Buddy
This is good for anyone who is new to a game system, but especially so for new players. Gaming systems are complex, and they can be scary. Assigning them a system buddy gives them someone to ask questions to as they learn the system. It will help things go quicker as their buddy can help with figuring out dice pools and skill rolls, leaving you free to focus on the game itself.
Focus On Outcome Not Specific Action
Along with the system buddy you want to try to keep the system out of the way when you can. Have the player tell you their desired outcome when you can, and worry about how the system handles it later. Don't worry if the system actually covers what they want, because the focus is for it to be fun and interactive. You can worry about the restrictions later. For now, get them involved.
A Bit of Advice Goes A Long Way
Don't be afraid to offer advice. You don't want to guide the player down a specific course, but you can give them advice. Show them multiple paths, let them pick which one, and go from there. Have other players give advice. Explain the context from the world. Go further than you would for most normal players. Why? because this person is new. When they know the world better they can hang with the other kids. For now, give the advice they may need.
Remember to Keep It Fun
Most of all, remember to keep things fun. Your game should be fun for those involved anyhow, but try to make it especially engaging for the new player to get them into the game. You want them thinking that the game is fun, not weird or awkward, and certainly not boring.
Remember that this is a game. If the first experience is that it is tedious, hard, confusing, or anything but fun you'll likely not keep the new person at the table. And that...that's a crying shame everytime it happens.