My standard plan is Roth conversions (not withdrawals) up to the top of the 15% tax bracket, then fill in with taxable and later with Roth. This transfers your taxable value into the Roth account, where you avoid taxes altogether. However, it is all a tax minimization exercise, so your specific situation will determine the best course for you.
My optimization of this is getting more sophisticated by the day as I modify my own custom software to maximize after tax retirement spending. My latest runs have several years where I'm supposed to convert just enough to avoid the AMT, which takes me to the middle of the 25% bracket. My RMD's still take me into the 25% tax bracket as well, so there's no way I can get everything out at 15% or lower. I also have to watch out for the exemption and deduction rollbacks above 300k AGI when Roth converting.
Other things to watch for:
* ACA health insurance subsidies, tuition tax credit, and other income limited cash back offers. Many depend on AGI, not tax bracket.
* 0% capital gains below the 15% tax bracket.
* Social Security timing and taxes, as well as any pensions and other income
* RMD's. Once they're under the 15% tax bracket you may be optimized well enough.
* Hidden marginal tax rate increases like exemption and deduction rollbacks, and some of the extra high-income add-on taxes. Some are dependent on taxable income, some on AGI or MAGI.
* AMT. Just another marginal tax increase. You can recover the added tax later, but you're out that amount for a year or more while it earns you $0.
However, don't despair. Much of my super optimization gains me pennies of additional spending per year. If you just convert as much as you can within the 15% tax bracket you will be 90% optimized.