OK, after all the brouhaha on the 'terrible tortures before crucifixion' thread I'll spout some opinion at length here. So anyone who's bored by a lot of meandering chatter, skip this.
-- Torture before crux --
The stamina of the victim should not be reduced too much. So before the crux may be a good time for all manner of humiliations, rape, and reasonable whippings, but no 'Passion of Christ' style shredder-floggings.
A decent whipping of the back, buttocks and shoulders will certainly increase her sensitivity to the roughness of the wood, and if she is suspended from the cross in a not too painful manner it may increase her inclination to move. If she's nailed, the pain from rubbing freshly whipped skin on wood will most likely seem rather inconsequential.
(When I say "nailed" I mean a victim who is carrying weight on the nails. That would not be the case with for instance the contemporary Easter "crucifixions" on the Philippines, were hands and feet of fully standing volunteers are merely pierced with slim nails and no weight rests on them)
So usually preparatory whipping should be done, for a public scenario it is a good introduction of the victim to the crowd and builds suspense and expectations, for the victim herself it is an introduction to her role as tortured object. For public humiliation and entertainment breast torture is also sometimes a rewarding option.
Lastly it all depends on the scenario, one can also imagine the opposite. Perhaps an individual of initially high status has been without doubt found guilty of treasonous conduct by a group of men in whose right it is to both pronounce the judgement, and carry it out; she might be lured by a forged communication along precisely the channels that she used for her treason, to lure her to a prepared spot, where a cross has been prepared just out of sight. There she is met by a group of people that encompass all necessary authorities, is accused and while the incrimination is still being read out finds herself being nailed to a cross before she can possibly comprehend the turn of events against her cause. Might be enjoyable as well.
-- Be cruxed and done or cruxed and tortured while hanging? --
One of the attractions of crucifixion is that it doesn't need anything other than the cross, the victim's own body and the force of gravity to effect fearsome torture. Of course the victim's body will always instinctively seek out any position where pain is momentarily lessened, and if additional pain is introduced by way of more whipping, branding, etc. she will certainly react, but for me this adds relatively little to the experience of crux.
If only a limited time is allotted for the crucifixion, any amount of additional torture might be applied like skinning, flaying, burning etc. but somewhere this will reach the point where the crucifixion is merely a suspension (however painful) to make the victim available to these tortures, that destroy her more quickly than the cross itself. These scenarios I do not find attractive, so usually I'm not a fan of garish Roman arena scenes.
So in general, no additional tortures except those that work together with the cross, such as sedile/cornu variations.
If it seems that the victim faints easily, and is wasting too much time in that state, or if she returns too frequently to a preferred position that appears less painful, she can be regulated with any implement of choice whether it's whips, torches, brands, spikes or whatever.
But none of this should damage the fullness of her ability to properly appreciate her crucifixion.
So even once she is on the cross, I still give my veto to the infamous violation by red-hot poker
If the cross is not used as an instrument of execution, but merely to suspend and display her, of course anything goes, but I'm not an enthusiast for the classic dungeon torture + execution process, so the victim would eventually come down again in one piece.
Honestly if I don't want to execute her by crux I don't want to execute her any other way, so she survives the day.
-- Naked before cruxed or stripped while on the cross --
Usually I would pefer the victim to be reduced to nudity or near nudity before being crucified. In a classic Roman public execution scenario , rags/loincloth might remain during the march to the sessorium just to draw more followers to watch the final stripping immediately before the crux.
If the victim is not aware that her punishment will be the cross, keeping her partially clothed on the way to her fate may be a good idea to keep up some hopes to dash later. Especially if she has perhaps seen slaves driven nude to the cross before, the fact that she is allowed to retain some clothing may make her believe that lesser horrors await her. Which may create a delicious moment of shock and outrage when she is confronted with her destiny on the cross.
Leaving the victim clothed while she is being fixed to the cross and only then slowly stripping her might make good sense if crux is done not as an execution, but for public display and humiliation (or the goal is to wrongly make her believe that she is merely to be displayed, with events escalating to execution later).
Simply put, once a victim has been brutally nailed to a cross, and experiences herself inescapably in the process of dying in a horrible way - for all matters of fact dead already - the additional impact of then being stripped is probably not that great.
If however she's roped up for public ridicule and display she may well beg honestly to keep a few rags as it still might make a genuine difference to her perception of self whether she is so displayed completely nude or with any remaining cover. If she was not an owned slave in the first place it might also be symbolic of whether there remains a chance for her to regain any modicum of social standing after her punishment or whether she is by the act of this punishment also simultaneously reduced to slavery, perhaps to be sold right off the display.
In sum I'm not too much of an enthusiast for the classic Roman execution scenario, because it is a predefined script whose purpose is the demonstration and elevation of the power of the state over the individual, and the Roman carnifex is just a cog in that machine. I never imagine mnyself in the role of a Roman carnifex.
Even the slave owner running a private crucifixion on a large, profit-oriented estate will often be following the prescriptions of sociodynamic and economic logic - transgressions that are generally expected to be punished with crux will follow that script as it will be the most cost-effective way of upholding authority, as opposed to perhaps later having to suppress widespread disobedience in an expensive manner if commonly cruxable offences are met with lighter punishment; or a profit-reducing large outflow of fugitives if on the contrary even the lightest offence leads to the cross, or punishment is used too randomly.
So I usually prefer scenarios where the crux itself is largely at the whim of an independent individual - including the full range from sparing the victim after some torture and humiliation, to an all-out brutal execution and letting the body rot on on the cross in the view of all. But it all depends on the situation, often I will prefer one where the progression of the punishment remains intransparent and unpredictable for the victim for as long as possible. However the inescapable procedure where the victim knows each step beforehand - stripping, whipping, deathmarch, nailing, dance unto death - and is utterly unable to prevent the progression may also have its appeal. How and where torture/stripping before or after crux is individually preferable depends entirely on the storyline, and I'll stop here because otherwise I'd actually have to write one.
For sure. 
