What are convenient and reliable ways to make the starter for rye bread?
I've received some portions from friends and family, which have always worked well. :-)

When I'm creating it from scratch, I mix 200g of rye flour, a little bit of yeast (which you can leave out), 1 tsp of salt, 1 tsp of honey, 1 dl of organic yogurt and 2 dl of water. I leave this mixture out on the kitchen table (at around 20C) for a day with a piece of wet cloth on top. After that I add 2 dl of rye flour and enough water to make the dough soft. This sits on the kitchen table for yet another day, after which is should look like a pool of lava and smell a bit acidic.

The honey and the yogurt is the magic touch that makes this starter work, according to my books and research. I've never done anything special to control the temperature or anything else.