If the business manager insists on a percentage of income, try to include a cap so that if your album goes triple platinum, your business manager does not get to retire. Another important member is an entertainment attorney. The entertainment industry is built on contracts. Lawyers write them and lawyers break them. Before you sign anything, it is advisable to have an attorney look at it.
Most attorneys charge by the hour or a flat fee.
Some, however, will want a percentage of the band's income. As with all other members of your entertainment team, avoid this if you can. An attorney who takes a percentage of a band's income may create a conflict of interest. Be wary of a lawyer who does this, even if they are merely shopping your tape. I don't know any lawyers who do work before getting paid.