You find a time machine and go back in time. What would you do differently with your startup?

• Things you overlooked when starting out?
• Things you wish you hadn't neglected (such as expenditures)?
• What should have been outsourced?

Here's what I'd change about my decisions:

Don't take on bad clients and customers. Go with your gut feeling from time to time. If you get bad vibes from a new customer, they'll likely end up costing you more in support and stress. ING Direct did this -- every quarter they would ask 1% of customers to take their business elsewhere (not in those exact words). These were the customers that used a majority of the support resources.

Validate your idea in under a week. I've spent too much time of my life building things without validation only to find out no one wants it. Here's my process now.

Create a team of advisors. This is especially important if you're a solo-founder. Your friend Steve from college doesn't count -- find people who have done the startup grind several times before.

Exercise. One of my biggest regrets. I spent far too many years eating crap until I started reading about how the human body works and eventually settled on a Paleo diet -- and my energy level went through the roof. I'd suggest reading Dave Asprey's Bullet Proof Executive blog.

Don't try to please every customer. It's always better to have a few who are fanatic about what you do best.

Do things that don't scale. Too often I had spent time building procedures and systems which were never used as planned. Just do some things manually even if they don't scale.

Hire an accountant from day one. It's easy to try to avoid this expense in the beginning, and then regret it once you have to raise money.

In a startup that I was an early employee in, things fell apart because we waited too long to get a public facing website up and running. We didn't even get started on it until the product was ready for prime time and it took months, during which time, we ran out of funding and the whole thing fell apart.

Looking back at it, I have three regrets.

1. I wish we had gotten started on the website much sooner, preferably at the same time we started product development. (That way we could have started gathering people who had some interest in the product in advance.)
2. I wish we had built it ourselves. We outsourced it to a web development company. They were kind of pricy, and the framework they had built didn't give us the flexibility to actually do some of the things we needed it to do. They ended up having to do a lot of custom work specifically for us, and send some of it over to us to do anyway. Our product wasn't web-based, but we had a good team of software developers with enough web experience that we could have built only what we needed for less time and money than they did. Not all companies will benefit from rolling their own website (for many people, using something like WordPress is a good idea). But in hindsight, for us, it made more sense.
3. I wish I had personally been more proactive as an early employee in the financial/funding side a bit more. It was a tiny company, and I was effectively the lead software guy there (but not a founder). It technically wasn't my responsibility to take care of this stuff, but had I kept myself in the loop, I could have pushed for changes in technical direction to help with the problem. (Like getting the website done sooner, and cutting out some features and going for an MVP much more quickly.)