Remember with temping, it's got to be taken first thing when you wake up before you ever get out of bed. Preferably around the same time each morning.
From what I understand about soft cups, they're actually used during your period to catch blood instead of tampons. They look like a diaphram, though, and they fit over your cervix. I imagine for TTCing, you'd put it in directly after BDing, to keep as many of the spermies in as you can?