The best way to smoothly tuck top meshes in?

Hi,
I am probably not the best person to answer this, as I still have to create a piece of clothing that I am completely somewhat happy with. However from looking at Maxis-meshes in blender, I'd say the answer depends on whether you want to create a top or a full-body garment. Their tops, which are intended to look like tucked in shirts, quite often are very flat towards the lower end, so they won't cause any conflicts with the garments of the lower body - I guess. The tucked-in effect is created mostly by the bump-map and creases painted on the diffuse. In full body garments too the actual moddeling of creases - as shown in the tutorial you linked to - is very limited in Maxis-garments. Most of the times it's just a ring of vertices pulled out a little and if you look at the garments in wireframe or solid mode they look very simple - again it's the bump-map and the way the objects are painted which give them a believeable effect.

And truth to be told, I am quite a fan of the paint-more-model-less method, it saves polies and it is much more effective in creating the illusion of certain material qualities. I cringe at how many video-games put so much importance on the modelling and so little on the painting.