While our entrepreneurial ancestors only had to hire a few service providers like an accounting firm, a legal firm, an advertising agency and decide which bank to deal with, nowadays we have to hire a lot more.

Just look at marketing alone: paid advertising, social media marketing, content marketing, lead generation, affiliate marketing, marketing intelligence, market research etc. Sure you could go the one-stop-shop route, but then you're often sacrificing quality of service.

It is fair to say that finding prospective companies to work with is one of the most critical things about running a business. If you are working with 10 service providers and you manage to get 10 percent better results than your closest competitor's service providers for the same 10 categories, their cumulative impact on your overall business performance would be 100 percent over that competitor.

That is why it is worth it to spend time finding the right service providers. If you end up working with the wrong ones, not only you will be losing on the money you spend with them but all the time and effort will be wasted, too.

To find the best service providers to work with, try these four techniques.

1. Talk with a former employee of the company you want to hire.

Find people who used to work at that company in a higher level position. (It's not hard to do with LinkedIn and online searches. Get in touch with your inner stalker.) I've found that I get a lot of replies when I do this because people love sharing their expertise and experience and are often flattered that I want to consult them for their expert opinions.

The best feedback I've received is from people who have left the specific industry I'm inquiring about either through career advancement or retirement. Because they're not in the industry anymore, their advice is more objective and they can offer great advice about who to work with, how to structure deals and other things to consider.

2. Reach out to the people in a provider's testimonials.

If your prospective provider posts testimonials on its site, reach out to the people in those testimonials. Even when they don't include a person's full name, as long as they include a company or some other identifier, it is often easy to find out who it is. When giving the testimonial, a person obviously makes it sound as good as possible. When talking about it over the phone, they are usually a bit more honest and will tell you the pros and the cons about working with that particular company.

3. Look at employee reviews.

You can tell a lot about a company by how it treats its employees. Looking at a company's employee reviews on Indeed or Glassdoor can give you a great inside view of the company and how things are going there, especially if you sort by date and look at the progression of reviews over time. Seeing what people have to say about management can convince you to work with this company or not. Obviously, you have to take former employees' reviews with a grain of salt, but they're still a valuable resource.

4. Imagine you're a journalist doing a profile piece.

If you're having trouble getting into the researching mindset, imagine you're a journalist tasked with doing an in-depth profile piece on this company. Read the company's newsletters and look at its Twitter and Facebook messages. Try to get a sense of how the company thinks and what messages it sends to employees and clients, how clients and partners respond and what events it goes to.

If you do your research, you can get great insight about your future service provider. Once you find a good provider, and believe in this company, check to see if it is a public company or not. Because if it is public or will soon be doing an IPO, then you might have stumbled upon a good investment opportunity, as well. Good luck with finding those service providers.