1. Get a pokemon with Flame Armor or Body Heat(or whatever the abilities are called, Slugma and Margmar and their evolution all have it). Having a pokemon with one of these abilities in your team will cut egg-hatching time in half, and you'll need to hatch a lot of eggs, so this is a must.
2. You'll get eggs faster than they'll hatch, so you need to store them in your PC. I find the most efficient way to do this is: Magmar/Slugma is in your team so you have room for 5 eggs, once the old man calls you about a new egg(the 6th), go to the PC a deposit the 5 eggs, get the egg from the old man and ride until you have 5 eggs in your party and one waiting for you and repeat. Once I filled a box with eggs(30 eggs) I took out the Ditto and other pokemon from the daycare in order not to waste money.
3. For egg hatching/Building up steps fast. Basically ride on your bicycle all the way from the top gate in Goldenrod to down next to the daycare, up and down, everytime I have 3 hatched eggs and 2 unhatched, I go to the PC and switch the hatched pokemon with new eggs.
Good luck, you'll need it!