Once you have decided that a search-engine optimization (SEO) strategy will help your online marketing, you need to know where to turn for help.

Not all firms holding themselves out as SEO specialists are legitimate, says Loic Jeanjean, director of web marketing with Vancouver-based Advisor Websites. So, it’s important that you know how to sort the good apples from the bad.

Here are four red flags that indicate an SEO company may not be on the up and up:

1. Sales pitches in your inbox
Exercise caution when a company first contacts you via email.

Many unethical SEO companies will send spam emails, says Cara Crosetti, account manager with Wickware Communications Inc. in Los Angeles. These emails, which often come from the U.S. or India, are usually vague about the types of clients and industries they specialize in.

2. Guaranteed results
Watch out for SEO companies that make guarantees that sound too good.

“If the SEO agency starts to make promises, and guarantees Page 1 results [your name appearing on the first page of search results],” Jeanjean says, “you need to run as fast as possible. No credible agency will ever make promises and guarantees. That’s impossible to control.”

Spending more money is not the answer, either. Some disreputable SEO companies will charge high prices for a “guaranteed” Page 1 ranking, says Cara Crosetti, account manager with Wickware Communications Inc. in Los Angeles. These companies will use unethical methods to improve your rankings, such as linking your website to an unrelated site — such as a retail store, for example — and often without that company’s knowledge. Or they might use a keyword they know will rank high but that won’t be used in a web search by anyone in your target market.

3. Excessive linking
Be wary of companies that recommend elaborate linking schemes as part of an SEO strategy.

If a company suggests placing links to your website on hundreds of web directories and sites that are unrelated to your business, Jeanjean says, you should consider that a red flag. The problem is that many directories are not relevant for search engines and therefore will not give your rankings the boost they need.

4. Vague processes
Ask about the company’s process to get a sense of its business ethics and competence.

A legitimate SEO company can describe its process in detail, says Crosetti. And that doesn’t have to mean a lot of jargon. A representative of a reputable firm should be able to tell you what tools it uses, the time involved, the type of tracking it uses and even what kind of competitive research it does.

“It feels like there’s magic involved in [an SEO strategy],” Crosetti says. “But there isn’t, and they should be able to articulate this.”

This is the first in a two-part series on shopping for an SEO provider. Next: What makes a good SEO company.