There are six bits that every carpenter should acquire as soon as they buy a router: a straight bit, a joinery bit, an ogee bit, a rabbeting bit, a flush trim bit, and a chamfer bit. With these bits, a woodworker can do almost anything from cut out room for an inlay to create permanent joints. Whenever possible, a woodworker should go for carbide bits over high-speed steel. They may be more expensive in the short run, but they produce a smoother cut and last longer, ultimately saving the carpenter money. When woodworkers own these six bits, they are well on their way to successful carpentry projects.
After that buy them as you need them for special projects