One of the first – and possibly the most important – lesson to learn about marketing is that it’s not something you do just once when building a business. Instead, entrepreneurs need to develop the habit of  promoting their business on a daily or weekly basis, and then stick with that habit over the course of years.

This might sound like too much work, but when done right marketing doesn’t have to take more than 15 or 20 minutes at a time, and it’s one of those activities that only start to really pay dividends after having invested hours and hours of time.

BTW, did you know there is a rule that says you should spend 20% of your time working and 80% of your time promoting your work? I would actually take that maxim with a grain of salt; in my opinion, not promoting yourself is better than engaging in marketing that could harm your business (zero gain always wins over a negative gain).

But the rule is still right in principle; you should spend time marketing. Here are six ways you can build your business, fifteen minutes at a time.

1. Reach out to former customers or clients, and ask them to give a testimonial (or better yet, post a review online).

Reach out to your recent clients and ask them if everything worked out and if they have any questions or problems. Once they are happy, ask them nicely if they will post a review or give a testimonial.

Having a solid core of testimonials on your site will only help you, and having multiple positive reviews on sites like Yelp will raise you above the competition.

2. Publish a blog post or newsletter.

A blog post can’t drive sales like they did back before Google killed Google Reader, but they can still be a good way to gain the interest of visitors to your website. A kick-ass evergreen post – one that is insightful and well-argued – can attract visitors even years down the line.

Similarly, a newsletter – while not as useful in the long term – is your chance to get the attention of subscribers where they live: their inbox.

If you are coming up short on ideas, here’s a tip: Take one of the questions your clients ask frequently and answer it in a blog post. Explain it in detail, and provide links to additional information.

Another way to write a great newsletter is to take something that happened to you and explain what can be learned from it. Be sure to focus on lessons that will help your clients.

I will be honest with you, though; a great blog post will take you more than 20 minutes. For example, this post you are reading right now took me around eleven hours to plot, research, write, and edit. That is a not insignificant investment in time, but I am hoping that the investment will pay off over the years as the post continues to be shared and read. (And I managed to improve my return by writing two different but similar blog posts based on the same research.)

3. Update/Refresh your site (this includes the SEO as well as the content).

Are your services pages up to date? What about the contact info, and your front page pitch?

Remember, the more useful info you share on your site, the more your potential clients will begin to trust you and reach out to ask for help.

4. Pitch a guest blog post to one of the sites read by a potential clients.

Go into your files and pull out that list. You know the one I mean – the list you wrote down of sites you contacted because your potential clients read them.

Brainstorm a few article ideas, and write up a pitch. Email that pitch to several of the sites on the list, but be sure to write a unique pitch for each site.

If you haven’t already contacted those sites, be sure to first send them an email introducing yourself and asking about their policy on guest posts. Some will say no, but many are used to getting pitches and should at least give you the time of day.

5. Update your profile on Google my Business, Yelp, and other similar sites.

When was the last time you updated your Yelp or Google My Business profile? (Do you even have one? Why not?) Are all the service descriptions, office hours, and contact info correct?

Consumers still find local services through search engines, but they probably won’t find your website first. Instead, they are more likely to find a service provider through review sites like Yelp, Zillow, etc. You need to make sure you have a good reputation on those sites, otherwise you will lose clients to competitors who do.

6. Read the daily HARO emails, and respond to the queries where you qualify as an expert source.

HARO (Help a Reporter Out) is an online service that helps journalists find sources to quote in their articles. It is free for reporters and costs the sources anywhere from nothing to $150 a month, depending on the service tier.

This can be a great way to get your name and business mentioned in a news publication, but since you can’t control how you are quoted there is the risk of being quoted out of context.