I am frequently ask, "How do I get my wife to let me Spank her?" I in turn have to ask, "Spank for Real, as in Domestic Discipline?" or "Spank for fun, as in sexual pleasure?"
I suppose there are a lot of factors? Spanking for fun would seem to be much easier to convince your partner that it's something you'd like to get into. Doesn't every husband give his wife a smack on her bottom from time to time? As hard as it sounds, or as easy as it sounds, you have to communicate. I've found that MOST people want to sexually please and be pleasured by their partner. If you want to spank your wife then she has to be told your desires. It very well might be that she's thought about being spanked but feels odd asking for it. The only way to get what we want is to go for it.
Now if spanking for "Real" is the question then it's different. First, in one way your wife "submits" to spankings, in that she lets you spank her. But, in another way it's more like "I spank, you submit to it". With my wife and me it was talked out and agreed upon first. In other words for me it was right up there on top of the list of things to agree about first.
If you're married already and haven't discussed Domestic Discipline then it's a bit different. If you've been, how should I say this, a wimp in your marriage then it's unlikely you'll be able to convert your wife into agreeing to a Domestic Discipline marriage. However, let's take my wife for example. She's very intelligent and educated however by her own admission she's a bit scatter brained and chaotic. She has a difficult time with organization and has no concept of how much time goes by. By her own admission she NEEDS direction. She has a strong desire to please me and when she feels she hasn't she gets upset with herself. She isn't into pain but would much rather get a good sound spanking to put her on track than to have me upset with her. She functions much better with consequences to her actions.
So, if your wife has similar traits to mine then you could probably win her over to a Domestic Discipline lifestyle. However, it does take consistency on your part. When it's time to spank you have to spank and not let her get away with things. I've found that the reality is the less I let her get away with things the more respect I get from my wife because I stand my ground and that's what she needs and wants.