Name your child. If you do not know the sex of the child, choose a gender neutral name. By naming your child, you will not have to refer to the child as it. You will have an actual name that you can use when you are talking about your child. Purchase a necklace or bracelet charm to wear.
Some people choose to purchase a charm with the birthstone for the month the child was miscarried.
It is a personal preference. Purchase whichever charm will help you to remember your child the best. Another perspective on this idea is to purchase a family ring with birthstones for your living children as well as your miscarried child. Plant a tree, rose bush, flower, etc. in memory of your child. I know that some people even plant an entire memory garden in memory of their child.