The Basis of Everything
There are many attitudes that will guarantee better built, better flying aircraft. Hold yourself to a standard that is as high as possible but doesn't make you give up. A good project has sub-projects. If you're doing it right, then the main and sub-projects are a lot of fun.
Building an airplane that isn't straight is not acceptable.
When you adopt this attitude you'll have a better understanding why I am so anal-retentive with some of my building techniques. If a former isn't flat then how do I know where on which edge to measure from?
An aircraft that isn't straight will never trim properly until it is. It doesn't matter how high end your computer radio is. The trim of a crooked model will always be speed-sensitive.
I hope I have just burdened you with a lot more work — devising ways of making sure all your work is straight. You're welcome.
Note for beginning builders: A crooked airplane will fly. Do the best you can. Your building skills will improve with experience and motivation. Your first few airplanes won't be perfect. That's ok and normal.
Building a model having anything that doesn't work properly is not acceptable.
Don't jury rig your planes. Make sure each part works as intended before installing it. Fix any problem you find. Don't convince yourself that the problem will work itself out on its own.
Building an airplane that is unnecessarily heavy is not acceptable.
You have to understand the properties of the materials you work with in order to use them efficiently.
Spend some time destroying some balsa (or whatever material) so you can learn what it can take. Bend it, drop it, twist it, hit it with a hammer. Do whatever you want to it so you can observe the results.
A nose dive into the ground is a lot more force than a soft blow with a hammer and many balsa aircraft survive the impact with nothing more than an easily removed dent or maybe not even a scratch.
How long it takes doesn't matter.
It may take six months or more to build a quality model aircraft. A well-built, easily maintained model requires more discipline and planning but if you take the time to build it right you can realistically expect the model to last until you just don't want to fly it any more. And if you change your mind you can put it back in the air with a reasonable amount of maintenance such as a new fuel lines, clevises and an onboard battery pack.
There's not good reason for a model aircraft to just deteriorate to the point where you're forced to ground and retire it.
Build your plane well and fly it to its limits