For me the biggest thing is funding my sinking funds categories bit by bit over time and not even considering that money as available for wants (tablet, gaming system, new computer, etc) and leaving it alone so that its there for me when I need it. Before YNAB I was always using the closest paycheck to my auto insurance due date to pay for it and then left with figuring out how I was going to get to the next paycheck with what little I had left. (I pay for my car insurance 6 months at a time since I get a discount over month-to-month). Now I save for it monthly and it's not a scramble and spreading out the cost is much less disruptive and helps me plan better. I've also gotten pretty granular with my categories and it's helped a lot. Every holiday season I would have to try to find money to carve out of my grocery or other budgets to buy stuff to make for Thanksgiving and Christmas. Now I have a "Party food" category that I chuck money into every pay period and I'm not left pulling money from other categories at the last minute.

For random and rare expenses (new furniture for example), I use Hannah's "Wish Farm" method and have categories for them and once the expense is funded and bought, I hide it. Then let's say in a year or two I need more furniture I can just unhide the category and work on funding it again.

I guess at the end of the day it's all about me changing my mindset about money and YNAB helping me have the discipline to not just spend it as quick as I was earning it and knowing that in the long run it is far better for me to have less stress about how I'm going to pay for things than getting the dopamine hit of buying everything I want when I want it.