Step 3: Allow proper concrete curing time...
CONSIDER A WATER BATH - Concrete is not as easy as mixing, setting and forgetting. It requires a period of time to harden, or 'cure'. Unfortunately, concrete is notorious for setting before the ingredients have had a chance to bond as securely as they could have. The result of a rushed concrete job is cracking, weakened durability and a crumbled project. I allow my projects to remain in the mold for a minimum of 24 hours, longer for thicker items, then carefully remove, and gently set the item into a deep bath of water for a minimum of one week. Okay, fine, I admit it, I stuff them into pond plant containers and sometimes in with the Koi, who is going to know? Often I submerge the entire project to avoid any damage. DON'T rush it, don't be impatient. The reward to patience is well worth it. A week. I mean it!
Many people also merely cover their projects with wet burlap (thanks, Cyoung13) or plastic wrap and such. Unfortunately I've never used such methods, so I cannot speak for them, but they are equally wonderful methods of preventing your project from drying out too quickly.
For those who simply haven't the time or the means to ensure your project stays moist, you might consider an acrylic concrete cure & seal, available in most home improvement centers in liquid form. Brush, roll or spray this formula onto freshly set (not freshly poured) concrete. Look for the deep yellow jug with green and black labeling in the concrete section. This product can be used on recent projects, or even existing concrete.