Better looping
Here's an easy one:
A fairly common construct is:
(({})<{({}[()]<...>)}{}>)
Where you want to loop n times but still keep the n. However this can be written as:
({<({}[()]<...>)>()}{})
to save 2 bytes.
Another fairly common paradigm is
([])({<{}>...<([])>}{})
Which will loop and accumulate the entire stack. Due to some fancy maths this is the same as:
(([]){[{}]...({}[])}{})