Taking ownership or "planting your flag" in an idea, work, or concept is often one of the best things someone can do. To sit in a room full of people and say, "This is mine. I will take care of it." Makes everyone in the room know you are the point person committed to making it happen. The same holds true when discussing documentation, processes, and ideas for long-range planning.
Almost every place I have worked has had a team that has made an assumption about the way things work. I have routinely found at least one widely accepted assumption to be the furthest thing from the truth. These institutional assumptions are very, very difficult to break down. It can take weeks and sometimes months to make sure everyone is in the loop. Demolishing institutional assumptions requires a constant drum beat that can be exhausting at times; but the drum beat is very necessary. Assuming something works a certain way is a sure fire to lose credibility if you are still maintaining that assumption after it has been debunked. Eradicate institutional assumptions; definitively prove or disprove operations of systems.
If you are going to plant your flag in something your knowledge of it should be one foot wide and one mile deep. You should know as much as possible about what you are planting your flag in (factoring in resource constraints). If you are not an expert in it, dedicate the time necessary to become the expert. If you cannot dedicate the time it takes to become the expert you should be mindful of taking ownership of it (perhaps you and another team member are best suited for the task at hand).
Do not be the person that makes assumptions. Definitively understand what you are doing and its impact on the things around it. Treat every task as an opportunity to learn. If you do not know, investigate further. You should also understand that no matter how much diligence you think you have put into your investigation there will likely be an outlier you missed. At some point during your research or investigative process you have to plant your flag. You could spend your entire career solving one issue. When you implement a change you acknowledge that you have the info needed to address the outliers that may crop up in a very quick and decisive manner.
Do not be the person that "cries wolf" because of an assumption. There is one in every medium to large-sized team. Every error message is not going to be solved by the same person or team within your group. Some times the error will have to be solved by you, the reporter. Other times the error is completely external to your team (third party vendors). Own the issue and get it resolved by whomever is the right team to solve it. Do not rely on others to consider your issue more pressing than the ones they are already working to resolve.
You must be mindful of your claims. Do not beholden yourself to your claims so much so that you create "pets". Pets are systems, processes, documentation, etc. that need constant feeding and care. Pets make for poor documentation and little understanding from other team members. Pets are the bane of a good (i.e., lazy) systems person's existence. "Sunlight is said to be the best of disinfectants." Be open and honest with yourself and your team members. Remember, you are not the expert or authority on all things; share the load.
Systems should be well documented, replicable, and immutable. Documentation should be written so that your junior person can follow along at 3 AM when all hell is breaking loose. Processes should be distilled down to the simplest, most intuitive level. If it is confusing to the person explaining it, it will most certainly fail. If you receive critical feedback, do not be defensive. Remain receptive and ask for help in improving it. If you plant your flag and build a fort around it prepare to have your fort burned to the ground. Someone will come along and find your weak point. Someone will come along and make your fort irrelevant. If there are forts in your environment, torch them.
Take ownership; be decisive. PLEASE, take control of your systems, processes, and documentation. Seek out new knowledge and incrementally improve on the things you have ownership over. Holistically address changes in an effort to maintain consistency. Do not be afraid to dive headlong into something you know nothing about. Your thirst for knowledge should be unquenchable. The fire within you should burn ever brighter. Make it yours. Take pride in accomplishing your work.
Plant your flag!