First, stuff the cavity below the cam sprocket full of rags inbetween rotating the engine and working on the stems.

When removing the caps, hold the valve stem with a pair of needle noses. Remove the nut at the stem, take off the retaining cap, then screw the nut back on. As long as that nut is on the top of the stem, you can drop the valve and it doesn't matter if you are TDC, although TDC is your goal. That just gives you a little safety net in case you miss it. I got my kit from Bergsma at ************** and they are excellent to deal with. The kit comes with good instructions and pictures, too. Good luck!