3. 7-Zip includes a wealth of settings but, for the time being, familiarise yourself only with the options under Archive format. The default is 7z, which produces smaller archives than Zip. However, to extract such archives, the recipient will need 7-Zip. In general, you should stick to the regular Zip format.
4. Also familiarise yourself with the options under Compression level. The default is Normal, but you can significantly reduce archive sizes by choosing Maximum or Ultra. Resulting compression will take longer - sometimes much longer - so this option is best used by those with particularly speedy PCs.
5. If you want to email several files, individually attaching or detaching each one would take you and the email's recipients a lifetime. Instead, 'stuff' the lot into a single, manageable archive. Hold down Ctrl and select all the files you want, then right-click any one of them and use 7-Zip as normal (see step 2).
6. Adding a new file to an existing archive is easy - you don't need to build the archive all over again. Right-click the file to be added, select Copy, right-click the archive, then click Paste. The new file will be automatically incorporated. If archive and file reside in the same folder, you can use simple drag-and-drop.