Wingovers: very weird - most people (me included) do them by weight shift with little brake applied except to yaw the wing around at the point where it has maximum bank angle.  So you weight shift right, wing banks right, dives and accelerates, you swing through and weight shift left as the wing climbs, wing banks steeply left as it slows, then you apply brake to yaw the wing around so that the leading edge is pointing at the ground (at this point the wing is travelling quite slowly and is lightly loaded) then you dive picking up speed, swing through and weight shift right, as the wing climbs and slows it banks steeply to the right and you apply right brake to yaw it round etc.

The problem with this kind of wing over is the exchange of kinetic and potential energy - you trade the speed gained at the bottom of the wingover for height as you climb and turn.  It can go wrong in two ways (typically - there are others):

Firstly, when you apply brake to yaw the wing round you may have to apply so much that the wing begins to peel back in an incipient spin.  This is ok because you are making it spin the right way, and so long as you release again when the wing is pointing towards the ground you are away diving into the next wingover.  If you don't apply enough brake to yaw the wing around, then you WILL sideslip towards the lower, inside, wingtip and the wing will collapse asymmetrically, even (or perhaps more often) in small wingovers.  The collapse is odd - because it is caused by sideslip - in that the wing sort of curls in from the tip, rather than folding in from the leading edge.  You slip towards the tip, there is nothing to hold it out there, so it curls in. 

Secondly, as you swing through the dive the wing rotates rapidly in the pitching axis - as you rotate the wing   forcing the leading edge upwards.  This can cause the leading edge to collapse - folding in in the normal way (usually asymmetrically one way or the other).  The only solution is to apply lots of brake which can keep the leading edge inflated but burns up energy - defeating the whole purpose of wingovers.

The other way of doing wingovers requires more ground clearance - because you gain a lot of speed by burning a lot of altitude, and turn through a lot of air.  The technique is surprisingly simple - you do a very aggressive turn one way then reverse it - that's all. The earlier you reverse the turn the more radical the wingover. The less brake you use during the wingover the higher your speed and the more radical the wingover. The skill is in timing it so that the whole thing is high-g's throughout.  If you get it right, you are rewarded by a high-g manoeuvre that is very smooth, but gets you well above your wing.  Easiest exit is to take one of the turns all the way round into a 360.  Timing is the key - if you leave the roll-reversal too late, then you can end up wallowing around with too little energy.  The earlier you put it in the more the energy builds up.  Doing these things tentatively is not good.....  you also need to be aware of your surroundings - sink rates get very high very quickly.  Much more radical, but also much more solid.

These manoeuvres allow you to practice the high loadings and unloadings, steep bank angles, severe pitching movements, that you will encounter unexpectedly during thermic flights.  Definitely a good thing - Those hideous moments of instability are so rare, even in strong thermals that you can't practice dealing with them by flying in thermic conditions.  Wingovers and other acro techniques are by far the best method I have found for practicing the kinds of techniques that allow you to fly safely in strong thermals.

Cheers,
Adrian