Classical, acoustic or electric?
A classical guitar has nylon strings and often a wider neck. A steel-string acoustic sounds bright but can feel firmer on new fingertips. An electric guitar needs an amp for its characteristic sound. Musical taste and playing comfort both matter.
Test comfort before looks
Sit with the guitar and check that it rests securely and the first frets are easy to reach. Are strings buzzing or do you have to push very hard? Ask a shop or teacher to check the setup. Size also matters for children.
What do you actually need?
A suitable guitar and tuner are enough to start. A case protects it while travelling; a pick can help, but playing with fingers works too. Ask a teacher or experienced player to help if you're unsure about a second-hand instrument.