Characters

Heart and Soul

Characters are the Heart and Soul of an Adventure. Even the smallest change in direction can lead to big changes over time. Think about your favorite Doctor Who episode, now try to run that episode in your mind but replace The Doctor for another incarnation with a different companion... I bet you can already see in your mind how that story would change just by doing that.

Before the game, the party and the Gamemaster should discuss what sort of game you'd like to play.

As long as you all agree and ensure that your characters all suit that game.

The Character Sheet

Let's put this out of the way first, after all I guess most people here came for the pre-made sheets and are not looking to create their own. I'll give you the short version first, and more details to follow if you so require.

The tl;dr

the ts;du (Too Short; Didn't Understand)

The list above might be very handy when you are in a pinch and just need that little spark to refresh your memory and remember what is what.

So now We'll provide the long version so you can learn more details about each of those fields.

Concept

It is like an awkward job interview where they come up with the most bizarre question — "describe yourself in a couple of words".
Think of what you have in mind for your character and try to boil it down to a couple of words. Something you could write on a business card or one of those networking badges.
Examples: "Doctor", "Probationary Police Officer", "Retired Bus Driver", "Trainee Electrical Engineer".

The Concept is something to always have on the back of your mind while roleplaying. If you ever feel stumped or overwhelmed by a decision your character have to make, it might help to think "What would a [Concept] do in this situation?"

When you bundle your concept together with the Focus and Goals, it's like the elevator pitch for your character.

Focus

Focus is usually a single word that describes their drive, passion, and motivation. It has its benefits as well as a downside.
Try to imagine what motivates them. Is it the need to prove themselves, a love of science, a compassion for those around them?
Examples: "Kindness", "The Law", "Compassion", "Hope".

The Focus should have both a positive and a negative side to it, as each will give your character bonuses for staying in character, and driving them towards their goal.

Example: Rory has Oath as a Focus, reflecting his hippocratic oath to save and protect lives.
As a positive, the player would receive a bonus (+1d6) when acting to actively try to save lives.
As a negative, Rory is expected to refuse to cause someone's harm. The player is rewarded with a Story Point for actively choosing to not join the party on a fistfight for example.

P.S.: If you are playing a long Adventure with many episodes, your Focus will change over time as your character grows and changes. (This will not be covered here, you may want to go buy the book to play this correctly)

Homeworld

This is where your character is from.
Not necessarily born, as you might be playing, for example, someone who was born on 21st Century Earth, but has been living for years on 51st Century Earth, so their tech level is more advanced.
Your homeworld directly affects your tech level, your character might find it really hard to deal with technology from levels above of their own. (Maybe sometimes even lower than... who living on the 51st Century would even know how to use a floppy disk?)

Find here a list of most commonly used Tech Levels:

Short-term and Long-term Goals

Everyone wants to achieve something in life, no matter how small. And to reflect this, every character has goals.
It could be anything — to explore, to find the love of their life, to further humanity, to advance the course of science, to boldly go where no one has gone before... you get the idea.

P.S.: Just like your Focus, your goals change over time. You either complete them or have some kind of life changing experience that steers you in a different direction.
Completing goals awards you XP and/or Story Points, which will make your character stronger. And just like the Focus, this won't be covered here.

Story Points

Story Points are very important.
They are a resource that you can use to influence the story. You can spend them to change the outcome of a roll, to avoid getting hit by a deadly laser, or even to introduce a new element into the story!
You start with a certain number of Story Points (usually 12, more about it later), and you can earn more during the game by roleplaying well, keeping to your focus, completing your goals, and some other ways as well.

There are big things that you could possibly do with a bunch of Story Points, there are ways to pool Story Points with your party... Oh, the bad guy tilted Earth of it's axis??? With a lot of creativity and a couple dozen Story Points we can fix that!
As expected, it would take a long number of episodes to accumulate that many points. Also they are supposed to be spent like this only at the most Universe-ending events of the sort, which may only happen at the very climax of a long journey.
And as any other game mechanic designed for long Adventures, we will be skipping going into detail. For now focus on spending your points to avoid damage and change outcomes on rolls.

More soon... sorry ran out of time