Alright first time using Eagle.
Bravo!
Couple things to consider and remember. This applies to design in general.
- Don't go crazy with trace width. Eagle's default width of 16mil is ok. 10mil for toner transfer may be problematic sometimes. Especialy with aggresive etchant sollution. 10mil is ok for a fab house.
- Keep an eye on separation between traces. Don't go below 16-20mil.
- Make sure that the solder pads of the components you are using are not too small. It's possible to enlarge them by modifying component package (library). They're often designed for a fab house fabrication, automated drilling. It's easier to damage a small solder pad while drilling, soldering, desoldering.
- Check the board and schematic for errors. For the schematic - look for the unconnected pins, overlaping connections.
For the board - run design rules check before making the board. Check the resutls for any clerance warnings, overlaping traces.
- Lay out the critical elements first - supply and in/out pads, potentiometers, switches,
- Draw outline of the enclosure or find a library that contains drawings of the enclosures/switches/jacks. There's one available for Eagle (on a Madban Forum).
- Do not hesitate to use jumpers instead running 10 inch long trace just to go around the IC or any other components.
- Keep separation between in/out pads and traces, especially on high gain circuits.
- Don't put tall components under a jack space.
- You can always install the LED off the board and take positive supply directly from the DC jack.
- Compare components you're goig to use with a footprints on the pcb. For transistors - check the pinout.