Here's one for you ...
Say you want a capital letter, rather than tapping the shift button then tapping the letter then tapping the shift button again, instead simply touch the shift button then slide your finger over to the letter of your choice then let go & you're sorted! No need to press the shift button afterwards ... I use this all the time and it speeds up text entry no end.
Can also be used for numbers and -/:;()£&@.,?!'" etc!
Give it a try ...
Also, I'm sure you know this one but in case you don't ... you can "shake" an iOS device to undo typing, deleting, cutting and pasting text ;-)