Yes, getting a cushion insert for your newly made crochet cushion is probably the best option. This is especially true if you want the cushion to be easily washable.

This is not always an available option. Maybe this cushion is not your average size or shape, so you just want to add stuffing.

Using stuffing on its own can have its problems. Bits of the stuffing end up popping out through the crochet.

There is a solution to this little issue and I used this method in my, 'Wish Upon a Star' cushion.

Instead of just the usual white fluffy stuffing, purchase some wadding. This is readily available from any fabric store and many craft suppliers. You can usually buy it by the metre/yard.

Most cushions are made in at least two pieces. Prior to joining the piece together, cut the wadding to the general shape of your cushion, just slightly smaller.

With a darning needle and thread, tack the wadding to the inside of the cushion.