The most common advice I've seen over the years runs along the line of thought of Do something new, Surprise your partner, Step out of the same-old stuff, Introduce some variety, et cetera.
While there's nothing inherently wrong with such platitudes as these, the practical implementation of them as suggested is fraught with danger. Let's examine the potential complications with specific examples.
Third Partner Surprise
Let's say that you and your partner incorporate role play and/or dirty talk into your lovemaking. Now, let's say that sometimes certain topics come up in the heat of the moment. One of these might be the introduction of a third partner to your sex life. The idea is hot enough to at least one of you that simply talking a bit about the idea during the session improves your lovemaking overall. Over time, this particular practice becomes part of a sex life that becomes a little routine, and you decide to seek advice in spicing things up a bit.
Pretty straightforward, yes?
So, you come across the advice above . . . specifically, Surprise your partner. The gears of your mind turn. You've always enjoyed talking about a third person during your sessions, right? How about amping up the excitement by introducing an actual third? Right on! So, a third is acquired without a discussion with your partner. Then, at just the right moment, the third opens the closet door . . .
"Who the hell is that?! What the hell?! Now I'm not enough?!"
Your partner wigs out, you are astounded by the reaction, and the third person is now highly confused and running for the hills.
As a co-admin of mine said, "Say whatever you want to to get me off, but don't actually do it. That's insane."
Let's say that you and your partner incorporate spanking into your lovemaking. At the right time, it's and incredibly powerful way to throw one of you over the edge of "almost there" to absolute gut-wrenching orgasm. But again, over time, this particular practice becomes part of a sex life that becomes a little routine. Your partner decides to seek advice in spicing things up a bit.
In this case, your partner comes across the advice Introduce some variety. A few blue movies your partner has seen have included a riding crop. Hmmmmm, interesting. In short order, a riding crop is acquired and hidden under the bed. During the next encounter, your over-excited crop-hiding partner pulls out the riding crop much earlier than the spanking would usually occur, and you freeze and stare at it.
Seeing a riding crop in your partner's hand is a compete turn-off. That fast, that simple. Do not pass Go, do not collect $200.
"Uuuuuuummmmmmmmm, no." Then you get up, grab your clothes, and get dressed in the bathroom as your naked partner stands outside the bathroom door trying to explain and apologize. Insulted and embarrassed, you're not listening . The last thing you can imagine is being naked with this person again.
Talking and Incremental Change are Key
While well-intentioned, the above examples led to damaged intimacy, broken trust, and damage to the sex life that simply needed invigoration. Sad, really. Counterproductive at best, unrecoverable at worst.
Humans are at their most vulnerable physically and emotionally in the bedroom, and abrupt changes/surprises can cause shock, fear, and anger that the conscious mind has trouble reasoning through. Fight or flight can kick in, and when it's caused by the most trusted person in the world, that can cause a schism that isn't the easiest thing in the world to repair. Add the baggage that people carry from the past, and sometimes the damage is unrecoverable.
Generating incremental ideas and then discussing them with your partner outside of the bedroom is the way to avoid this pitfall. Doing this lets you gauge your partner's receptivity, let's your partner know that you're open to new things, and also lets your partner know what to possibly expect in the future.
After all, you wouldn't jump from the top of the mountain to the bottom, you'd climb. And if you were the guide, you'd talk your companion all the way down.