Starting with a guard that leaves a slightly longer length is advisable for beginners. Guard #2 (1/4 inch or 6mm) is a popular choice as it offers enough hair length to work with while still being manageable and forgiving for new users. With the #2 guard, you can practice blending and do some fade without going too short too quickly. As you gain confidence and experience, you can explore using shorter guard lengths to achieve different hairstyles and fades.