Generally you should be firm about your position, but have reasonable expectations. If you have any evidence which you have reason to believe the other side is not aware of, it should not be used or discussed at mediation if the insurance company and their lawyers are not offering a reasonable amount, or what you think is a reasonable amount for the injuries you sustained. If they come close to the number you have in mind, raising the issue or revealing the evidence may push them over the top and bring them up to the number you have in mind. You will get nowhere arguing with the defense lawyer. The mediator may be proactive or may simply be a messenger that carries offers and counter-offers bacnk and forth. The mediator in Florida cannot give legal advise and I would suspect that it is the same in Alabama. In short you should have number in mind about settlement but be prpeared and appear as if you are prepared to go the distance through a trial so that they know you mean what you say when they offer a minimal amount and you suggest that the case be decided by a panel of jurors. However, in thend at mediation you control your own case and once you go to trial it will be up to the jury to decide your damages and what value to put on them.
If both sides are in mediation in good faith, you should be willing to talk openly with the mediator and be willing to compromise your position. A successful mediation typically results when neither party is happy with the result. Keep in mind that BOTH sides must give so if the other side is not compromising, it won't work. Mediation only works with all parties participate in good faith.