Hi,
I ll help you in with so far knowledge i obtained
1. For high speed boards, plan the stack-up properly, understand your board size, if its smaller then plan the signal layers and corresponding number of planes for it. Tracewidths, material used, spacing will help you in having controlled impedance and check for manufacturing feasibility with the vendor.
2. Plan your VIA's that goes to your board, like thorugh holes or blind via's any u need. Note that cost is important so through hole via are cheaper but carefully plan for the stub. Wat is the frequency of the board. say if it is 1GHz the stub length will affect the performance of the board.
3. Component placement is major part. Understand the thermal flow, air flow of the board for components. Try placing your components so that trace length is maintained minimum and plan for EMI issues at the initial stage itself.