The most Important thing for a company is the face out that your customer´s will see. The logo is the face out that´s making people remember your brand when they need your service. There are different types of logos out on the market, abstract Logos, Mascot Logos, Combination Logos, Emblem Logos, Lettermark Logos, Pictorial Logos and Wordmark Logos. So knowing what type of logo you are looking for is a BIG helper.
Fonts are also one of the things that´s nice to know what you want. Serif or Sans Serif? Extreme fonts? Make sure to look around and tell me when we´re doing the brief for your project. Colors are also something that I want to know, and if you dont know right now? Give me some info on what colors you like at least, otherwise I´m just going to use a color that I think is matching your brand.