In a restaurant, it is good to give between 5 and 10% tip directly to the waiter.
For a small favor, like carrying luggage or parking a car, a few Egyptian pounds would be appropriate. Not more than five.
Often times in Egypt you will find someone tending to the bathroom to keep it clean. Giving them one Egyptian pound is an appropriate amount.
Tipping your tour guide and vehicle driver is completely optional but should be considered if you're provided with great service. If you decide to tip feel free to give what you think your experience was worth.