We are starting with a few things that have to be decided out of character before starting.
First you have to decide on your sponsor for the New Horizon project.
There are five choices:
AbadarCorp (Grant): As usual, AbadarCorp is throwing money at the situation. You might be AbadarCorp employees doing their god's work and civilizing the wilderness, or godless folk hired for their expertise with promises of a rich reward at project's end.
Starfinder Society (Exploration): The Starfinder Society wants to know of any mysteries on this new planet. You are likely agents of the Society, drawn from its diverse ranks and set off exploring for knowledge and glory.
Veskarium (Expansion): Perhaps this new system could eventually be the next part of the Veskarium? You might be loyal patriots of the Veskarium claiming this charter for their home, or outsiders sent to settle under promise or threat. You might even be former Veskarium prisoners, put to work on Project: Horizon in exchange for commutation of your sentences.
Xenowardens (Conservation): The Xenowardens are interested in being in tune with the natural environment. You likely share the organization's views or have something to gain from working with them, such as access to natural resources.
Zenniledie Labs (Experimental): Zenniledie Labs is a medium-sized Triaxian corporation founded and run by the silver dragon Zenniledie, who seeks a cure for the draconic disease that killed their mate. As scientists, you are part of their grand research project. You might be researchers in the draconic CEO's employ, employees whose skills make them well-suited to charter management, or sympathetic souls moved by Zenniledie's plight.
Each of the five options have different starting benefits, and some events in the game will depend on what you choose here - though, not one is better or worse than the others.
The rules for charter development are here:
Second I'd like you to consider what the initial focus of the charter should be and what bonus traits your charter should start with (step 3 and 4).
Third you could take a look at the downtime rules. There will be time when your characters are not doing any exploring and such where we want a long stretch of time to pass. If you want, you can use the downtime rules for that (but it's not mandatory if you don't want that hassle).