Note: This information is general in nature. Your own situation may be different.
Let's get one thing out of the way up front - if you ask a lawyer, they will tell you that you need a legal advice for every music deal you make. Technically, they are right. They can make sure all of the deals you make are air tight, and if you have your own music lawyer looking out for you, they can help make sure that you get a fair shake in all of your music related agreements.
Now, let's get real. A ton of music deals happen without an legal advice at all, especially in indie music - largely because no one has the money to pay a lawyer. That doesn't mean that you are doomed to getting taken advantage of every time you put your name on the dotted line. As a general rule of thumb, if the person you are entering into an agreement with has legal advice, or if the contract they are asking you to sign was clearly drawn up by an attorney whether or not they have a lawyer on retainer, then you should definitely get legal advice (INDEPENDENT legal advice - don't just go to their attorney). On the other hand, if neither party involved in the deal has a lawyer, and if the deal is relatively simple, just write down the terms of the agreement and have both parties sign. You should do this with the knowledge that your deal will not be as solid as it would be if you had a music lawyer involved in writing it up, but for most simple deals, the potential risks are far, far outweighed by the cost of hiring an attorney.
If you think you do need legal advice, or if you feel like you just need to run some ideas past someone, check out any free or low cost alternatives available to you. The Musicians' Union and other musicians advocacy groups will be able to help you find this kind of information.