Many personal injury lawyers charge a contingency fee. This means that if you receive a settlement or win a damage award, you'd pay a percentage of that amount to your lawyer. There's no standard percentage that lawyers earn, but it's usually around 33% of what you recover. If you lose the case or recover nothing, you won't have to pay attorney fees.
There can be up-front fees involved, too. If your lawyer needs to hire investigators, expert witnesses, or the case requires travel, you might be responsible for paying those costs before you recover any money.
Be sure to read the fine print in any retainer agreement you sign with a lawyer. There might be a little room for negotiation, depending on the size of your case, the defendant, and the likelihood of success. Don't be afraid to ask a prospective lawyer any questions you have before you sign the retainer.