Need a service but I don't know much about it

As a decision maker in my startup I want to be better informed when contracting someone for a service, especially.

Years ago I was led to believe anyone with a computer and good eye could easily make a logo within an hour for a couple of bucks, but through the years I have learned about the process of creating a symbolic representation for a company requires rigorous research, brainstorming and more that an hour. To save me years of learning something the long way, I currently search online for information on who does the service and how they do it ,but the how can get quite consuming, and not sure if this is enough to keep me well informed.

There is a lot of us that face this problem especially in startup where you might need a lawyer, accountant and other professionals and know nothing but a basic understanding of what they might do.

What are the key questions I should try to answer when making research online on a foreign service?

As you have stated yourself

To save me years of learning something the long way, I currently search online for information on who does the service and how they do it.

You actually may not be able to get at how they do it because without the person telling you their methods it will take you years of following them around to figure this out (if they even let you). Generally speaking you are not looking at the methods employed by the particular service provide but at the results they have produced.

For example you have a certain need for your business and you found a provider you can ask for recommendations from them or find people who have used this provider in the past and see what they have to say. Granted "past performance does not guarantee future results" but on average you can be reasonably sure that if most people would recommend this provider then you have a better chance of getting what you need then with a person with no or poor track record.