1. Failure is part of success. - In my first days of Kerbal I didn't have any idea what I was doing, then I had my first Minmus landing that made all my 'prototypes' worth it. 2. Scott Manley is your friend. - Not trying to be cliche, but this man has taught me so much, mods or not, he is one knowledgeable fellow. 3. Bigger is not always better. - Grabbing an Orange tank and strapping on 6 radially attached orange tanks and some boosters will probably give you a little bit of a hard time. Instead research Asparagus staging. It is a Godsend. 4. Check your staging - For how many times I have caught myself having to load a quicksave because of staging problems. So simple but yet we forget. 5. Think outside the box - This game rewards creativeness. Getting some more complicated designs from players on the forums or spaceport can give you some ideas to get the juices flowing. I have downloaded tons of user crafts, but I usually don't fly them, I take them apart to see how they work.