The madfermentationist (aka @oldsock ) is a great resource.
The funny thing is, sour homebrewing was a bit of a black hole for a long time. Oldsock and others are helping people to understand the different aspects of sour brewing and how they compare and contrast to regular brewing. You are not far behind the curve. I will try to provide a little intro about the organisms used. Generally, sours contain very little hops (often aged hops), as the microbes used are inhibited by hops. The grain bills and mash schedules are as varied as any other beer.
Accidental sour beers are usually not very good, which means that creating a drinkable sour batch requires as much planning as goes into your house ale (or more if this is a new road for you).
Unfortunately, brewing a good sour beer requires nearly the opposite of many common ale brewing practices. For example, after you boil your red rye, you would chill it to 65F and aerate with air or oxygen. For most species of Lactobacillus (the organism primarily responsible for the sour flavors), you will want to keep your wort at 100F and avoid aeration. This example is as much of a generalization as saying you always chill your wort to 65F for an ale. There is as much, or more, variability with the organisms used in sour brewing as there is with the various types of beer yeast. This can make things complicated.
One of the new trends in sour brewing is the use of a single pitch, analogous to pitching a particular type of yeast in a batch. This approach certainly simplifies a sour batch. Crooked Stave in Denver makes a lot of Brettanomyces-only beers. There could also be situations when you would just pitch a single species of Lactobacillus, then drink it directly. While easier, this approach may not make the best sour, or provide the flavors you are looking for. This is where things get complicated (if you want them to, I guess). Many sours have a balance among many different flavors contributed by multiple organisms, eg. a balance between lactic acid and acetic acid. One of the aspects of sour brewing that I find very interesting is how the vastly different microbes used in sour brewing can work together, and tend to make a better product when they are used in tandem. For example, Pediococcus (a close relative of Lactobacillus) produces a slimy booger in beer, often referred to as a "sick beer." Brettanomyces can use this gooey mixture of proteins and carbohydrates as additional nutrition, thereby cleaning up the sick beer and developing more flavors.
A way to start experimenting with making sour beers is to find a sour style you like, and work backwards. I like LaFoile from New Belgium, so last year I found a recipe for a Flanders brown, made the batch, grew up the dregs from an old La Foile batch (when they still had dregs), pitched it and let it sit for a year. It was good, definitely, but it was no where near La Foile. This approach is tricky, because you will (probably) never be able to exactly mimic the fermentation conditions used in a commercial batch. This may be analogous to wanting to make a clone of Budvar lager, which is always fermented at 45 and lagered at 34, but you can only ferment at 50 and lager at 38. The wooden vessels often used in larger breweries to make sour beers have their own characteristics based on organisms in the barrel and often, the oxygen content. So maybe some of the beauty of homebrewing sour beers, is that you own it. It is difficult for homebrewers to make consistent, repeat batches of the same sour beers. Each one is likely a little different from the next, and this can be due to a slightly higher or lower mash temperature (most of the sour bugs can eat the sugars that are unfermentable for Saccharomyces), slightly more or less oxygen (most species of Lactobacillus are anaerobic and get weird when oxygen is around), a different proportion of one bug to the other (a higher proportion of Pediococcus vs. Lactobacillus), or whether or not a type of Saccharomyces yeast was used (many Lactobacillus species to not produce ethanol, so Sacch must also be added).
Even though things can be a bit unpredictable sometimes, many of the normal brewing concepts are very relatabe and important for making good sour beers. For example, when brewing those normal ales, many influential aspects of the process are well known and thus controlled. It is well known that you can or should ferment a saison at a higher temperature compared to a lager, and that you should aerate with oxygen for 60-90 seconds, or that wheat is appropriate in some styles and not others or that noble hops belong in certain styles. These things are managed to make good beer, and the same applies for making good sours.
We may eventually get to the point of having very high quality, repeatable clone recipes for sours like we have for many other beers. Until then, you kind of have to go for it and see what your "house" can make. Find a recipe, take good notes, brew it, take notes, pitch something that you have taken notes on, then ferment it a take some notes. After a year, taste it and take some notes. Then post all of those notes on HBT.
Good luck and cheers from behind this wall o' text.
