Congratulations. You did your homework, and found a personal injury lawyer you want to hire. That will ordinarily involve entering into an attorney fee agreement, which will specify the terms of your relationship with the lawyer and how the lawyer will be compensated for services provided.
Most of the time, a personal injury lawyer will be retained on a contingent fee (also called "contingency fee") basis, meaning that the lawyer will receive a percentage of the proceeds obtained from the case, through litigation or settlement. The maximum contingent fee that can be charged varies depending upon your state, as some states cap contingent fees either by statute or by rules of attorney ethics. Depending upon the jurisdiction, a contingent fee for a personal injury lawsuit is likely to be a third of the recovery, and in some states may be as much as half of the recovery. (Contingent fees are generally lower in workers' compensation cases, where they are more tightly regulated.)
You should note that it may be possible to negotiate a different contingent fee, or to negotiate different contingent fees depending upon the state a case is at when a settlement is reached. For example, an attorney who demands a 50% contingent fee may be willing to reduce that amount to 33.3% upon request. Or a lawyer may agree to reduce the fee if a settlement is reached before a lawsuit is filed. However, some lawyers (including some of the best) will decline to negotiate their fees.
When you "sign on the dotted line" to formalize your relationship with your lawyer, and enter into a written retainer agreement, make sure that you review the details of the agreement. If there are additional concerns you have, such as how quickly you can expect the lawyer to return your calls, or whether other lawyers will be involved in handling your lawsuit, you should try to resolve those issues before you enter into your retainer agreement, and you may wish to ask that concerns you believe to be important are reflected within the agreement. (Otherwise you may find that your attorney takes a different attitude toward your concerns after the agreement is signed, than the attorney expressed to you beforehand.)