Growing in height
growing in weight
or developing in puberty
To me, the crucial part here is "before you begin" - this means that we're being asked for the steps before you write the first letter.
First, it's good to have a topic (1) for your paragraph - or a leading thought if your paragraph is a part of a bigger piece. This will ensure you stay on this topic and not digress.
Second, it's good to have the content ready (2) - so the arguments and the examples you want to give.
Third, it's good to have a structure(3) - this way your paragraph will be easy to read.
If you have those before you even start writing, your paragraph will be well-structured and well-written!
