I keep a couple of sets each of measuring spoons and measuring cups. That way, if I'm cooking and my teaspoon gets wet, or full of sour cream, I don't have to stop, run to the sink, wash and dry it. I just grab another one and keep going.
Liquid Measuring Cups. Splurge. Buy the glass ones. It really is easier to measure when you can see what you are doing. I have a small (1 Cup) and a large (1 Quart) cup.