Firstly who is the target audience? Logos can be for the community at large or a more targeted specific group or groups. Pepsi will pretty much sell to anyone but Adobe does not aim their marketing sights on children for example.
The graphic design style used will be a function of who sees the end product.
Another question to ask is what sort of emotions and feelings will the logo design seek to stir?
We would use a different style for reliability as opposed to excitement- the styling of say a law firm’s logo is inherently going to differ from one for an entertainment company.
Hipsters and corporate types want and expect different things as one can readily imagine. While this is a simplified example, the point holds true.
The primary question really is “what does your logo tell me about your brand, how does it make me feel, and most importantly does it make me eager to buy your product or service?
The current state of the brand strategy will also need to be established. It may be that there is an existing overall color scheme in place which is not destined to change, and the logo will need to adopt from the existing color palette.
There may be a pre-existing logo that just requires reworking for a more modern look. Good creative agencies can sometimes accomplish this by adding three dimensional qualities to what came before, so viewers will still recognize the logo but will become at least unconsciously aware of the update.
An important point to remember is that a professional logo design is key if you are in business. Clip Art or something designed by your neighbour’s cousin comes with a high price over time.