IK (inverse kinematics) is one of those things that seems to frustrate a lot of us. For the most part I leave it turned off and save my characters with it turned off, but there are times when it is wonderful. More often than not it just goes berzerk on me, and the poor model is left with broken ankles and gross distortions. But then there are times when it works exactly like it was intended. I just never know when I will get the perfect pose and when my model will look like a train wreck.

My guess is that there are better and worse practices when using IK, and I am hoping that some of you have worked these out. So, do you use IK? How, when and where?

I use ik when I need to keep the hands locked to something that is itself fixed, like say a ballet dancer holding onto the practise bar.

I found that using the dials to move the hands or feet works best and slow movements  to allow the IK calculations. you may in some cases need to dial in the bends of the collar and shoulder if the limb looks unrealistically bent. same for legs. turn in or out the thigh. 

Extreme positions will move the chest and hip.

One thing that happens with me is that I will position the hand with IK on and then turn IK off, and the figure goes into contortion mode.

My primary best practice tip: always save your scene before engaging IK. Then turn it off again before saving the altered scene. ;) I have several instances where engaging IK has somehow made the scene permanently unusable.

That said, IK has many useful applications and I'm glad to have it available when needed.  

Agree with Markshum regarding the hands and posing them to hold onto something. Where this really works well is when you need to position all 4 limbs like riding a bicycle or a motorcycle. Speeds up getting the feet positioned on the peddles of the bicycle or foot pegs of a motorcycle in addition to the hands on the handlebars.

I am not a score keeper and others with more knowledge can maybe help here. In you sig it says you are using Poser 8. Older versions via my experience had the on off jumping issue at random times. But from PP2012 or PP2014 I can't remember that issue and turn IK on and off all the time with no issues in more recent verisons.

Does anybody remember any kind of recent changes to IK in say Poser 9 or after?

Quote - Older versions via my experience had the on off jumping issue at random times.

Yeah, Poser 7 here - I should have specified that to qualify my comments. I don't have enough experience with P9 to say if it's improved.