Do you always put them up the same way or change depending on location/situation ? Do you take a spare length of guyline for such a time or sort your lines for all situations ?

My tarp only goes up one way. However, I do have the guy lines a bit long, and have marked a couple of places where I would use a clove-hitch around the peg to allow variation in the height of the bottom edge to suit conditions.

I hold my hands up and admit to being a tarp anorak ... I make a set of lines for each tarp that can be easily switched between different points so allowing different pitches. Usually 2 x 2m and 8 x 1m lines will allow you to bicycle pretty much anything.

1 or 2 ways normally. A wheel or tree at each end, or handle bars at one end only if its too windy and needs to be low

Long guy lines attached at all 3 end points of each end... if that makes sense. I can move them if needed but havnt needed to yet

Tend to go for an a-frame as its quick and easy, and if its raining or windy or both I'll just drop one end and tuck the corners under. The tarp has a line at each corner and I carry six others, including two long ones, which are great if I can find a nice thick drystone wall or an old barn or something to pitch up against. I used to carry a spare length of dyneema in case I needed it, but I never needed it so it stays at home these days.

a tarp anorak

Now there's a new(ish) product idea )

I used to pretend I was like Ray Mears and could just chuck up a tarp anywhere. After a few damp nights, poor sleep as it flapped about or just faffing for ages in the dark when I was done-in tired I figured out a couple of basic pitches using the bike (wheel in or out) that also work with a tree as a support, then marked the tarp so I knew which bit went where and sorted the lines accordingly. Goes up in a few minutes now, and works. Often now I take one of the bearbones poles to take the place of either the front wheel or a stick.

Previously had a terra nova rectangular tarp and mostly set it up A frame. Did use a half pyramid a few times but then it rained quite heavily one night and the bottom part of my bivi bag got wet and stopped breathing leading to condensation inside so never set it up that way again. Now have a silwing which will always be set up A frame.