It's hard to give really specific advice on this but do you have friends who work in tech who've filed patents? If so, they probably have worked with a patent attorney hired by their company to convert their invention into a patent application. Ask about their experience, whether the patent attorney properly understood their invention, whether the patent attorney was responsive, etc.
In general, as a patent attorney who's worked both in large international law firms and in a smaller firm (patent boutiques) that deals just with patent prosecution, my general advice would be to try and find a good patent boutique. In general the quality of the work will probably be about the same and the patent boutique will probably charge you less money.