Not all dishes are created equal, and some materials can be ruined by the dishwasher. Make sure you have the knowledge about what is dishwasher safe, and what you should wash by hand. Some dishes/utensils are too expensive to constantly replace from dishwasher ruin.
Here are some items to NOT put in the dishwasher:
– Sharp Knives. The dishwasher can dull and warp your blades, so don’t take the chance on your expensive knife set.
– Nonstick Pots/Pans. The dishwasher will rid it of the “nonstick” quality, so hand wash these at all times.
– Wood Utensils/Bowls. The wood can warp and/or lose its finish in the dishwasher.
– Cast Iron. Running cast iron in the dishwasher can strip it of it’s “seasoning” that you’ve worked so hard to build up.
– Copper Utensils/Bowls. It will ruin it’s shine, or (if its just a copper coating) will strip it off.
– Crystal. The dishwasher can chip it and cause it to lose it’s shine.
Follow that do not list, and you will save a lot of money in replacing kitchen items in the long run. I also recommend putting things like Tupperware, plastic measuring spoons/cups, and anything frail and/or cheap plastic on the top rack of the dishwasher. The heat can cause these things to warp and wear down, and the top rack is typically more gentle. You can hand wash to be safe, but they are cheap replacements so I typically risk it with these types of items.