If I may make a suggestion for someone is doing the plugs for the first time. Do one at a time. Unplug the wire, remove and replace plug, plug wire back in. Just remember which ones you did and didn't do. Easier to do this way than trying to figure out mixed up wires. Plus less chance of dropping anything in with only one hole open.
Some other suggestions (as may have been said)
1. Use anti-seaze on them
2. Do not overtighten!!!
3. After removing the wire boot, blow out around the plug with an air compressor before removing the plug.
