now your listening

Hi all I do like my DIY and have ordered 30 metres of skirting for my weekend job in my bedroom. (Guys calm down just fitting wood nothing that exciting) and I have a saw to cut my external mitres do I cut the internals the same? As someone in my office said I should scribe the internals is this right? Please answer me before Saturday as I will be getting my kit on (not off) for my skirting experience.

Thanks all.

Donna