One thing you can do right off the bat (and I would do this before starting the actual placement/layout phase of the design) is set up the design rules for the project using a known good template. Sunstone circuits, which is a fabricator based out of Oregon, has an Altium-specific design rule
download on their site. At the very least, this will make sure you're not trying to do anything in your design that an "ordinary" vendor won't be able to manufacture. If you're not sure exactly how to use the design rules, or want to know a little more about how Altium uses them, there's a
good overview here.
After looking at your schematic, here are a few things I can comment on that will help you with EMI-related design decisions
- It looks like you're using an external +/- 5V power supply. Make sure you physically separate the board connectors from any high-frequency components of your board (oscillators, fast-switching logic gates, etc). This will reduce the amount of noise pick-up between the two regions of the board (if you're using a switched-mode power supply, there's always a chance that could "jump" over to other traces in your design).
- If you can swing the extra cost, use internal layers for your Ground and Power planes. Punching straight down to the planes reduces the trace length from components to their supplies (great for EMI reduction) and the planes will inhibit EMI pickup.
- When you're done routing the board, add ground pours to the top and bottom copper layers. Again, this will inhibit EMI pickup.
- Route your critical traces and components first (high-frequency lines, analog circuitry, SMC connectors, etc). The pushbuttons on your schematic are very low priority compared to the oscillator line for your PIC
Even though the datasheets linked above might seem generic, make sure you stop a few times during the layout phase and check to make sure you're not violating any of the rules. Designing PCBs is part art and part science, but if you ignore the best practices, you're setting yourself up for failure.