My partner and I have both been self-employed for a bit, I do love it and will have a hard time going back to a regular job.. Flexibility for travel/vacation offset the annoying parts.

Here's a few tips that helped me:

• Setup a bank specifically for receiving your invoice payments, separate from your personal bank. Every time you get paid, split the money you need for taxes out to the savings account. Pay yourself on a regular paycheck cadence from the remainder. That way your personal budgeting isn't messed up by irregular payments, and you always have your quarterly payments saved up.
• Get a good tax person, someone friendly who won't mind emailing/chatting informally. Avoid a big corporate accounting place.
• Insurance is expensive as hell, but also tax advantaged. Ends up being not so bad once you get over the sticker shock.
• One thing that sucks is not getting paid when you're on vacation. I work around this by planning out my hours in advance for the month, so if I have some planned time off I can still get a view for the monthly income, where to make up those hours, etc.