You need a clear idea of the aim of the amendment. It can be useful to write it out in plain English. For example:
"To require the Secretary of State to consult the NSPCC before appointing the Children's Commissioner."
Most legislation either
- requires or enables people (and/or bodies) to do things, or
- requires them to do things in a certain way, or
- forbids them from doing things
Think about how to express your intentions in these terms.
Once you have an idea of your aims, you can contact the Public Bill Office and have a discussion with one of the Clerks working on the bill.