In Texas, personal injury cases are decided by a preponderance of the evidence standard. The more evidence you have, the more likely your allegations will have credibility and weight.
It is crucial that your collect evidence as soon after an injury as possible. Using your phone, take photos of the area where the injury happened, especially of any road hazards, property damage of both vehicles and or debris fields, and any visible injuries. If cars are involved, get a picture of the other license plates. Take a picture of the government issued ID of other people involved.
Your attorney may find additional evidence in the Discovery Phase of a lawsuit, but the more evidence you can provide, the better.