uCHobby has an article up about checking component placement on PCBs before ordering. If you’re planning on having your circuit design professionally fabricated, it’s vital to do a thorough pre-check to get a better idea of the final product. There’s not much worse than receiving a box full of expensive custom green coasters (unless of course you’re into designing coasters) when you expected a functional board.
Doing an easy PCB pre-order check – Link
HOW TO – Manufacture your own PCBs – Link