Loads of good advice. Just a few things I want to add.
Our spankings are never about our real life. If I fancy doing the whole punishment role play, I just make stuff up. I would never want to change his behaviour (or he mine) to get or avoid a spanking.
As an example, the last one I gave him was “because last time he spanked me, he wasn’t hard enough, so I had to show him what it should have been like.” Total nonsense, but it got me a harder one later 
We often use the “maintenance spanking” excuse. ie you haven’t been spanked enough recently, so you need an example to remind you of what you want to avoid. Another possibility is that I “confess” to something, and I only ever use the word “confess” if it’s made up tosh, so as soon as he hears that, he knows I want a spanking, so the role play kicks off.
I did a “petulant brat” character once, including dressing up, and that earned me a spanking, but again, it is all made up tosh and characters.
And sometimes, the real me just wants a spanking because I feel close when I get one and I want that feeling. Then, there are no characters and it is just him and me and a loving closeness and I adore it.
Secondly, I would suggest a range of tools. We never use a single tool, instead, doing a few with one, then another, then another etc. I think a range of sensations is nice, and it helps to prolong a spanking.
Thirdly, chose your areas carefully. I only like my bum, boobs and pussy to be spanked. Nowhere else. Tried other places and it wasn’t fun. With him, it’s bum only with the occasional clip of his cock or balls, but only occasional. Those are hard limits we never break.
Fourthly (and this is for your wife), you need to trust who you are spanking. The first few times I spanked my husband, I was “pathetically wimpy”. His ass can take far more than I expected, so she needs to trust you to tell her how far to go. My husband reads me so well. So many times, I’ve been almost about to use my safe word and he’s stopped spanking me. She’ll learn your limits and soon have you where you need to be. (Plus practice makes perfect, and both he and I can take much more of a spanking now than we could in early days.)
Fifthly, just enjoy it. Fundamentally, this is a loving act like all the other female led stuff you do, so you can both just bloody enjoy it, and it will likely add so much more to your already great relationship.
Have a great time, build up to it and please report back as you do, as I love you hear your updates.