I've often traveled, and virtually always alone. It's okay. You can go where you want to, and move around at your own pace.
It is said to have a first aid kit, and to scan you documents like passport page and email it to yourself. I've never done these, and never needed to.
But, a solo traveler can be an easier target for robbers. Luckily that has never happened to me. Hotels, and other accommodation places, invariably don't cater for solo travelers. So, the rooms will be for at least two people, and one person would have to pay extra, a single supplement.
A solo traveler can feel out of place, if at a place where everyone else is with others. One also doesn't have anyone else to share the travels, experiences with.