Glasgow's Laws of Computing

There are no silver bullets.
The likelihood of failure of a project increases as the square of the number of unproven techniques/products/people involved.
Quality is not free, but it is cheaper than the alternatives.
If you can't describe it in writing, you can't build it. If you haven't described it in writing, don't try to build it.
(Corollary) If it's so small it doesn't need documentation, then it doesn't do anything worthwhile.
We don't build products, we build prototypes.
There are no silver bullets.
Complexity is usually the result of either lack of knowledge or lack of adequate thought.
Any salesperson claiming 90% reduction in development time is 100% lying.
Normalize your design fully, but don't expect to implement it that way.
There are no silver bullets.
A change affecting n modules in your system will be implemented in at most n-1 modules.
There is no such thing as a "one-time quick and dirty" program. Build every program as if God and everyone will see it. They will.
If you can't take pride in your work, don't bother doing it.
Two years after a system is implemented, no one will remember if it went in on time, but everyone will remember if it went in clean.
NEVER NEVER NEVER modify a vendor package.
There are no silver bullets.
Beware of any system or product, the name of which tries to imply something about the goodness or quality of that product.