I've learned to follow four simple rules in my IT career:
1. Be honest.
2. Be direct.
3. Be polite/professional.
4. Don't take it personally if your ideas are vetoed/changed.
Practice these and you'll earn the credibility to influence others when it hits the fan and you're asked how to correct it.
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Just my $0.02 from over here in the cheap seats of the peanut gallery - please adjust for inflation and/or your local currency.