I was born in the UK, but my mother was born in the US, making me a UK and a US citizen. (I later emigrated to Canada and became a Canadian citizen, as well.)

If you are one of the record number of Canadian-US dual citizens wanting to renounce, consulates here have a two-year waiting list. Fly to Europe, where waiting lists are a couple of weeks to a couple of months. You will have to pay a staggering sum IN CASH, in new, not-too-large denomination bills. Do not attempt to pay by credit card!

If you are asked why you are renouncing, DO NOT mention the word "taxes." It is a serious crime to give up your US citizenship to avoid taxes, and you will be barred from entering the US forever. You will have to get an accountant to fill out your final-year US tax return, because it is so complicated.
If you have not been filing US tax returns, apply for a tax amnesty IMMEDIATELY. If you don't, you could end up having to pay thousands of dollars in fines, even if you owe no money in taxes. You will also have to fill out forms called FBARs if your total bank deposits were over US$10,000 in any year. Again, thousands of dollars in fines if you don't. You only have to go back five years.

How did it feel to give up my US citizenship? Freeing. I spent four years in the US, and I recognized then what is now stunningly obvious: far too many Americans are bigoted, racist, misogynistic, rude, self-centred, and breathtakingly ignorant.