Redoing your child's bedroom can really be a lot of fun. In many ways, you can let your creativity run wild here. There is a wide variety of styles and colors to suit every kind of space imaginable.
For a younger child, it can be great to play around with bold, bright colors, snazzy designs, and themed furniture to make the place one that your child just loves to spend time in.
An older child is likely to be a little keener to be involved in any decisions made about their room. They will probably want to select their own furniture, or at least be consulted about it, after all, they will be the one spending the most time there.
Depending on your child's age and personal preferences, they may want to opt for something themed, such as a racing car bed or princess style furniture. However, a critical consideration here is versatility. While your child may be wildly into these things right now, you know better than anyone how swiftly their likes and dislikes can change.
If you are looking for something that is really going to last -- and given that we are talking about furniture here that is certainly likely to be the case -- try to gently steer your child away from stylized youth beds or furniture that is too obviously associated with just one kind of look.
Instead, it's much better to guide them towards more neutral types of furniture that can more easily be adapted to their ever-changing needs and tastes. Such furniture is likely to be much more enduring and could even be repurposed elsewhere in the house at some point. Either way, you won't find yourself buying new items every couple of years.
In terms of materials, classic solid wood or wrought iron probably works best. Keep in mind that dark wood tones or metallics often do well in boys' rooms, and light wood tones look good alongside more feminine colors.
Make it up to your kid for not letting them quite get their own way in terms of the furniture by allowing them to get creative with the bedding and soft furnishings. These are both a lot easier and cheaper to replace when your child ages out of the themes and designs.