Should I work with a lawyer to obtain the Portuguese Golden Visa?

I would definitely recommend that you do. You’re making a sizable investment to gain Portuguese residency (and eventually citizenship), so I wouldn’t recommend taking any chances during the application process. While the lawyer fees aren’t insignificant, they are much cheaper than making some formal error, making a bad investment, or one that ends up not qualifying. Many law firms charge upwards of €4,000-€6,000 for the primary applicant. There are also cheaper options, but it’s worth asking if certification of documents, translations into Portuguese, and/or tax representation is included. The application for dependents is cheaper and averages often between €1,000-€2,500. The renewals of Golden Visa for the main applicant (at the end of year 2 and 4) average around €2,000-€2,500. Expect to pay up to €20,000-€30,000 in lawyer fees for a family of four (for the initial application and the two renewals) when hiring one of the more expensive firms.