I'd be careful with anything electrical such as spark plug wires, distributor cap, coil,etc, (maybe use saran wrap to protect these areas?) Also the remove the oil filter and block the intake with a towel. Don't use a high pressure wash as that will certainly cause problems and make sure the engine is cold. Use degreaser and loosen stuborn areas with a toothbrush instead of using water pressure. Did a engine wash years ago with my 92 Nissan Sentra first and found water had entered the spark plug wells, it was no fun removing the water and drying it with a blow dryer.