Correcting text on iOS: fixing capitalization

I re-write and re-organize text frequently when I type longer messages (emails, StackExchange posts, etc). That means that words that were originally at the beginning of a sentence might end up in the middle, or vice versa.

I have found that it is nearly impossible on an iOS device to change the capitalization of a word without retyping the entire word. If I try to highlight just the first letter (or to drag the highlight end-point), then it snaps back to highlighting the entire word.

Is there some technique I am missing to do this?

Or maybe some custom keyboard that would make this simple? (I haven't used any custom keyboards yet.)

Some of this is in built-in apps (iMessage, Mail), others are in 3rd-party apps ("Alien Blue" client for Reddit, Facebook app).

In case it matters, I use an iPhone 6 and an iPad Air, both with latest iOS 8.1.3.