Creating a story arc
Player stories are absolutely as valid and encouraged as any moderator created story, though it may seem intimidating.
Creating and running a story needn't be a complex affair. In fact, some of the best RP will come out of very simple ideas - those other players interacting with that story will give it body and life. However, it's good to be prepared for every eventuality. To that end, here is some guidance you may find useful.
The idea itself
Check that it is plausible and fits within the lore. What's the goal of the story?
Get yourself a moderator
Hope for the best, but plan for the worst!
The simpler the story, the less likely you are to need a moderator's intervention but you really have to tell a moderator at the start. Don't worry, they're not wanting to steal the crown - but let them know so they can give you any pointers. Most plans need a little tweak to get them on track with the lore, or to ensure that you have their backing if you end up in hot water: a good case in point is if your character is about to become a double agent type - if you work for group A, and are going to infiltrate group B, you absolutely must let a moderator know. If only you know, and you get caught out in character by group B or - worse - group A, having a moderator aware of the situation is very likely to help you get resolution.
Perhaps you want to have players be rewarded for their participation. Moderators can and do award prestige for situations that cause character development at their discretion. If you want people involved with your story to receive some and it falls into this category, then this is of course possible. Also, if you want to have credits available, or salvage, or other resources that the moderators can provide, then all this should be discussed and agreed up front. The economy of INSILICO is a carefully calibrated ecosystem,
Balancing your influence
It's absolutely encouraged to get involved with your own story, but be sure that you are not metagaming with it. This can be difficult, as you may be creating clues and setting up interactions which will inform your player as well as others. Be sure you are playing fairly, and if you are in any doubt you can ask a moderator
Barry looked agitated. "The hell with it all. Let's take down the head of AGIS! They've got to pay for what they did!"
Paul slammed his empty mug on the bar. "You've had too much. We gotta get going. That safe in the warehouse isn't going to open itself."
Your story has to be plausible. It absolutely is possible to take down the head of AGIS, but not without an awful lot of planning and consent and firepower and people and consequences. Keep it simple.
How will it start
What's the start point of your story? How will it get moving? A loose broadcast. A rumour in the breeze. Grizzled veterans brooding in a bar, trying to make a credit.
Check in with your moderator at regular intervals. It doesn't have to be every day, but perhaps once a week give them a little update and raise any issues or concerns if it isn't going to plan. Having waypoints in your story is likely to help, and help you plan a contingency if and when it veers away from your original idea. What if a player disappears OOCly - they cannot log on, or they are no longer playing? Most of the time, it can be moved past, but working with your moderator will help to pick a possible path around it if isn't easy.
How will it end
What conditions have to be met for you to consider that the story arc has ended?
What if it all goes wrong?
Sometimes stories simply can't be completed. Retconning or voiding the roleplay that has gone before can get difficult, or even be impossible, and anything like that is always a last resort.
Example story - a walkthrough