Knowing what you know now, what would you do over if you could restart your business today?

I posed this question to several successful advisors and their answers were insightful. Here are a few of the hard-fought mistakes they say they've made, and the ensuing lessons they've learned.

SAYING YES

"I've learned to say 'no' to client requests," says Jonathan Foster, CEO of Angeles Wealth Management in Los Angeles.

Early in his career, he says, doing business was all about doing what the client wanted. Now, he says, "If you say yes to one-off requests, you end up with an unleverageable business model, and will likely deliver sub-par output to clients, because you have gone outside your core competency."

Foster is a longtime industry executive whose resume includes a stint as president of Carson Wealth and Peak Advisor Alliance. About three years ago he formed his own RIA and, free of legacy issues, "was able to implement many of the great ideas that have been kicking around in my head during my previous 25-plus years in the industry."

OVERPAYING FOR SENIOR TALENT

Foster actually offers a second do-over as well.

Historically, he says, when hiring talent, he paid heavily for experience. Now, however, he says he hires smart (and less expensive) young people and then gives them an uncomfortable level of authority.

"This may sound like a big risk, but if you don't give them authority, they won't learn and they won't stay," Foster says. "Let them feel, and be, important to your business."

TAKING ALL CLIENTS

In the early days of his RIA, says Eric Bishoff, new clients just had to pass the "fog a mirror" test.

Given the chance of a do over, "I would focus like a laser beam on a niche market and work with the type of clients I like to spend time with," says the founder of Bishoff Financial Group in Worthington, Ohio.

With this singular focus, he argues, he "would have fewer clients, more consistent revenue and a good work-life balance."

He also says this type of focus would make it easier to build a consistent service model that would meet the needs of his clients and his own profit needs as a business owner.

Along similar lines, advisor Tommy Williams in Shreveport, La., says he would set an account minimum sooner. In the beginning, he'd take anyone who walked in his door; his minimum today is $1 million.

GOING IT ALONE

"I would hire a professional coach," says Dave Purdy, founder of Wealth Management Midwest in Forest Lake, Minn. "Business is moving at the speed of light these days and without a professional coach I feel it would be too easy to get off track."

It's not just advice he'd seek though; Purdy also says he would outsource everything he could from the get go. That's exactly how he's running his business today after "learning the hard way," he notes. He contends that's helped him offer "over-the-top client service ."

FAILING TO TRAIN YOUNGER STAFF

One big do-over for Carol Busche, an Ameriprise Financial advisor in Brookfield, Wisc.:

new advisor training.

Rather than being thrown into a bullpen with a phone and a phone book, Busche says, "The right way to come into this business is to partner with a veteran advisor who is willing to train, mentor, and eventually sell their practice."

She's putting that in practice with her current associate advisor, who started as an assistant and later became a paraplanner and then a full-fledged financial advisor.

Working side by side with Busche, the associate advisor now understands the business inside and out, and is in line to succeed her.

So what's your do-over? Pretend you have a clean slate with no legacy issues. Knowing what you know now, what would you do differently to build your business?

Now decide which actions you are going to implement -- and get busy.

Steve Sanduski is founder of BelayAdvisor.com. Follow him on Twitter at @SteveSanduski.

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