Test unzipped location for select files to ensure that unzipped worked.
Create the .maintenance file in current WordPress base.
Copy new WordPress directory over old WordPress files.
Upgrade WordPress to new version.
4.1. Copy all files/folders other than wp-content
4.2. Copy any language files to WP_LANG_DIR (which may differ from WP_CONTENT_DIR
4.3. Copy any new bundled themes/plugins to their respective locations