The most effective way to soften your water is to use peat moss, but it will also reduce the kh buffering that exists in your system, so you have to monitor your ph regularly to make sure it doesn't crash.
As for myself I use Seachem Discus buffer which has a phospate base buffering system, and I found it to be excellent, as long as you only have 1/4 of the dose stated in the packet to your new water, instead of the tank.
A few ways to soften water, as DJ said peat moss softens water to a degree but for my money if you want serious amounts of soft water then you will either need an ro unit or ion exchange resins. I don't mean those cheap nasty water softening pillows you regenerate with salt, but a quality cation and anion resin from a good water treatment shop. Overall if you are planning on a lot of water at a cheap price per liter then i would visit a water treatment specialist with a sample of your well water and get him to set you up with a ro system. They are not cheap to set up but are cheap to run and don't need a lot of maintenence. If you have modest water requiremnets and live in an area with clean air then perhaps you can just collect rain water, it is very soft.
DJ, the buffers you mentioned do not soften water, they alter the chemistry somewhat but if you check the results witha conductivity or tds meter afterwards it will show no reduction in the water hardness.