The day after I quit my stable job to start my own design business in 2008, the economy collapsed. I was terrified that I had made a life-ending mistake.

My life didn't end and this summer Diligent became the longest-running job I've ever had. I've made plenty of mistakes over five years and each one has made Diligent stronger. Here are my five biggest and what I learned from each.

Mistake #5: Playing to weaknesses instead of strengths

There was a lot I didn't know when I started off. I had adequate confidence in my creative ability, but saw "business" as a dark cloud of terms like assets and liquidity darkening my horizon.

My fear became determination to learn.

That meant I had to design a complete set of financial forms from scratch. I needed my own balance sheet, profit and loss report, and cash flow analysis. I took time to understand the formula behind each calculation. Turns out a balance sheet has to balance. A-ha!

There were two things wrong about this strategy:

1. I wasn't really learning business. I was learning accounting and a specific set of fill-in-the-blank skills that missed the forest for the trees.
2. More importantly, my skills as a designer more or less stagnated during this period. I wasn't playing to my strengths, I was playing to my weaknesses.

Eventually, I retired my beautiful spreadsheets and bought QuickBooks. A few months later, I contracted a bookkeeper. It's nice to have a basic understanding of double-entry accounting but learning it was about fear and not about making my business stronger.

My proposal template is another matter. It has become my repository for hard-won wisdom and gets redesigned whenever I have a business epiphany, which is pretty often.

Mistake #4: Trying to do too many things

In the first year, Diligent Creative did everything: web design, print design, logos and identity, video production...

That meant a single day might start scouting a shoot location followed by a brainstorm to channel a client's grand aspirations into a color palette and end with discovering the latest Internet Explorer bug while trying to jam in a kerning session for an annual report.

I was saying yes to everything and turning into a Walmart.

If I wanted to get better at anything, I needed to focus. Designing a logo is like getting hired to name someone else's baby; not something you do on the side. Concentrating on web design created a path to become an expert.

Thanks to a liberating lack of meetings, most of my days were devoted to design. I also read articles about web typography, flexible grid systems, and agile development. The profession was evolving quickly and I pulled myself to the bleeding edge.

I redesigned my proposals to incorporate modern workflow techniques like data-driven design and iterative enhancement, both now core aspects of Diligent's identity.

Mistake #3: Surrendering authority too easily

It was 5am and I was crawling to bed after fixing a final batch of bugs before a site launch. My infant daughter stirred in her bassinet. Three hours later, the client had delayed launch and added 100 new "bugs" — some of which were major changes, none of which were clearly thought out, and all of which were out-of-scope for the original proposal.

They were a major client and I didn't want to lose them. I swallowed my pride and got to work. Two weeks later the site was delayed again. It did launch eventually but only stayed up for nine months before the CEO decided to take the company in an exciting new direction and shut it down.

If I sound like I'm blaming them, I'm not. It was totally my fault.

Imagine you go to your doctor and list your symptoms. She listens carefully and then, based on years of education and experience, writes a prescription for 200mg of Whateverex.

"I'm sorry," you say. "For what I'm paying you, I'm going to need 500mg at least. And some X-rays. And an appendectomy."

How much respect could you have for your doctor if she just shrugged and said okay? And then complained about her "patients from hell" over drinks with other doctors?

Clients don't hire Diligent to do whatever they ask. They're looking for someone they can trust, to whom they can explain their problem to and who will find the right solution and can defend that solution as sufficient when pressed.

After parting ways with the major client, I redesigned the proposal template, quietly adding a clause to the contract terms:

"We reserve the right not to do something if it seems like a bad idea."

Mistake #2: Not knowing how to price work

I joke that Diligent has a boring business model. We do stuff for people and send them a bill. The truth is that "and send them a bill" can be really tricky to figure out.

If your toilet is overflowing, you call a plumber. Actually, you call several plumbers and you ask for estimates. They might say, "A toilet? That's $50." or they might say, "We're $100 an hour with a one-hour minimum."

Call a web designer, "It depends."

There are reasons, of course, like our tools are still being invented while hammers are 2.5 million years old, but pricing is the thing I've struggled with the most at Diligent.

• Flat fee. At first I charged a single cost for the entire project. Clients appreciated knowing the cost upfront but scope creep was a huge danger (I had yet to learn Mistake #3) and I was on the hook.
• Charge by the hour. Lawyers seemed to have it right. Unfortunately, laboring over details looks suspiciously like running up the bill. I ended up eating a lot of hours to bridge the gap between what clients were willing to pay and what my sense of quality required.
• Value-based pricing. Diligent now prices projects based on the value they deliver to the client. It's challenging to calculate, especially with mission-driven organizations who have a non-traditional "bottom line", but aligns incentives and combines an upfront cost with a high quality product.

Of course, the proposal templates had to be totally redesigned.

Mistake #1: Trying to do it alone

I never wanted to be a solo show. Three of us were going to quit our jobs together but when our mutually determined deadline came, I was the only one who jumped.

Despite all that I had learned over my first four years, there's a psychological toll to being self-employed that wears on you. If you're not careful, it wears on your entire family. I was determined to show my daughter that work was a thing that could be creative and rewarding and could feed your soul.

A couple years in, I got really close to finding a new partner. She was a good complement in skills and a peer in industry experience. We had conversations about hard questions and decided to give it a go. She went to her boss to give notice. He promoted her. She got her own department and a director title; I couldn't hold it against her.

It was Compostmodern, sustainable design conference, that I first ran into Martha. She was directing a group discussion and I kept thinking, "she really knows what she's talking about." Afterward I introduced myself and it turned out she worked for my old employer. "Wait, you're Stan?" she asked. "Do you have the PSD for the blog template?" Even then, it took a year of conversations and half-starts before Martha joined Diligent full-time.

With Martha onboard, Diligent is kicking into high gear. It's a strange feeling the first time you see an invoice go out to a client that you didn't send. Overall output is up and for the first time, systems need to be in place so we know what we're doing.

Sounds like we need to redesign the proposal templates.