There are various bases for bringing a lawsuit against someone. Perhaps the most common reason is for negligence. If you have been injured by someone else's careless or negligence, you can sue that person in a personal injury lawsuit.
In order to win your personal injury lawsuit based on negligence, you must prove the multiple and necessary "elements" of your case. In fact, you must prove each element by a preponderance of the evidence. "Preponderance of the evidence" essentially means more than 50%. That is, the jury must think that the facts you present are more likely true than not.
The elements you have to prove are:
1) Duty. You must prove that the defendant owed you a duty of care. For example, we all owe each other a duty to make sure we are aware of our surrounding when driving and not crash into each other.
2) Standard of Care. You must prove what the standard of care is that the defendant should have measured up to. A simple example may be that one standard of care when driving would be to drive within your own lane. That is a standard, a rule, an expectation, by which we all are judged.
3) Breach of Duty. You must prove that the defendant breached the duty that he owed to you. You will do that by showing that the defendant failed to measure up to the standard. For example, if the defendant drove over his lane marker, then he may have breached his duty of care.
4) Causation. You must prove that the defendant's failure to satisfy his duty actually caused the harm you are claiming to have suffered. For example, if the defendant drove over his lane marker and crashed into you, then you may be able to show that the crash that he caused was the reason for all the pain and discomfort you have been suffering.
5) Damages. You must finally prove that you have actually suffered. You must show that the defendant actually owes you something--money.
To give yourself the best chance at winning your personal injury lawsuit, you should talk to an experienced personal injury lawyer as soon as possible. A knowledgeable personal injury lawyer will be able to go through various elements of your case and show you how to put them all together and build a strong case of negligence against the defendant.