Fine-tuning "Open safe files after downloading"
The preferences file is located at ~/Library/Preferences/com.apple.DownloadAssessment.plist

If the file doesn't exist, then create it and include the following:

&lt;!DOCTYPE plist PUBLIC "-//Apple Computer//DTD PLIST 1.0//EN" "http://www.apple.com-PropertyList-1.0.dtd"&gt; 
&lt;plist version="1.0"&gt; 
    &lt;dict&gt; 
        &lt;key&gt;LSRiskCategorySafe&lt;/key&gt; 
        &lt;dict&gt; 
            &lt;key&gt;LSRiskCategoryExtensions&lt;/key&gt; 
            &lt;array&gt; 
                &lt;string&gt;docx&lt;/string&gt; 
                &lt;string&gt;xlsx&lt;/string&gt; 
            &lt;/array&gt; 
        &lt;/dict&gt; 
    &lt;/dict&gt; 
&lt;/plist&gt;


To exclude Zip files, add the following to the preferences:

&lt;dict&gt; 
    &lt;key&gt;LSRiskCategoryNeutral&lt;/key&gt; 
    &lt;dict&gt; 
        &lt;key&gt;LSRiskCategoryExtensions&lt;/key&gt; 
        &lt;array&gt; 
            &lt;string&gt;zip&lt;/string&gt; 
        &lt;/array&gt; 
    &lt;/dict&gt; 
&lt;/dict&gt;


More info at: Source