Don't give a retainer over without great forethought. If they have a certain retainer before taking a case, be sure you can be refunded what is not used. Talk with other lawyers if the initial costs are too high and the lawyer won't work with you. Prepare yourself before you meet with a lawyer. Their rates are hourly. When you are spinning your wheels with disorganization, your lawyer is charging you for it. When you're prepared, you will take up less of their time, and thus pay less in legal fees.
If you don't feel at ease with a lawyer, do not hire them. This holds true with their fees too. Also, when it comes to the retainer, do not give the lawyer a blank check with your signature. Get an cost