A good quick "gateway" sour might be a berliner weiss, if you not familiar with it, its a very light wheat beer, next to no hops and is soured with lactobacillus, they typically finish out very quickly and are very light sour and spritzy, in fact they are great on a hot summer day
other than that somthing like a flanders or a lambic will take 1yr+ and sometimes you get snake eyes, some of the best flanders/etc Ive made have been a blend of multiple batches to produce a better overall product
as far as recipe formulation for a b weiss its pretty much just a hefe on a diet fermented with a german ale yeast + lacto, for the others you need to make sure you have a lot of sugars that are unfermentable for sacch in there to feed the brett/pedio/lacto/sherry flor/etc otherwise it wont get as funky and sour
a decent primer on wild beers is "Wild Brews" by Jeff Sparrow, other good resources are
the burgundian babble belt
the mad fermentationist
city brewer
brettanomyces masters project
ryanbrews
among others