Winded & distracted statuses, bondage, perception, arousal, cunning, position, and the specific clothing article in question are the deciding factors for stripping someone else, roughly in that order.
Pain damage has no effect unless you've done enough to deplete their stamina bar and cause them to become winded, in which case your stripping will automatically succeed. Likewise, stripping a tied up opponent will always succeed; however, keep in mind that a character who has higher speed and acts before you may break free that same turn. Perception and cunning are often related to accuracy, and you're more likely to strip an opponent who is turned on. Position matters: sitting on or holding your opponent from behind will improve your odds. And finally, some pieces of clothing are more difficult to remove than others, like the bulky trench coat. I couldn't tell you how to order the clothing your opponents actually wear though.
That all being said, there are several skills that will strip your opponent completely. Sleight of hand is a level-up perk that has decent success rate. Naked bloom is 100% and non-interactive, though I'm not sure if it destroys the clothing, probably does. The Ordered to Strip status from Valerie's skillset is usually reliable, or you can follow up with pain attacks to wind your opponent if they refuse to strip. Tempt Undress... I think is a vanilla skill? It might be a mod one, can't remember, but it completely strips both characters. And as the game goes on, your opponents will use strip tease more anyway, so clothing becomes less of an obstacle the longer you go. Dexterous has no trade-off that I know of.
Regarding builds, it doesn't matter. Balanced works. Specialized works. The hardest part of the game is early-mid, where you can be stun-locked and abused to rocket your opponents' progression past your own. Once you're past that bump, you can build pretty much any way you want, including getting every skillset, and still be competitive. Power and seduction are more potent early on, but cunning brings about good utility after you're situated. Advanced skills are all up to personal preference/roleplay, though some are certainly better than others.
I will say that it's not a tightly-balanced game, and you can make it as easy or difficult as you want, depending on build and skill selection. For example, you never need to use slap or knee again after unlocking kick because kick is just better in every way, but you might want to do so for RP reasons or whatever. Just have fun, don't get wrapped up in min-maxing. It's not that kind of game.