some common mistakes in website

• Duplicate Title Tags: a quick and dirty way to identify whether or not a site has an issue with title tag uniqueness or significant duplicate content issues.
• Web Crawl Errors: not only find 404 error pages, but the source of those errors as well.
• News Crawl Errors: details reasons why pages may not be getting indexed in Google News. Information provided here is pretty specific – ranging from “date not found” to “article disproportionately short”.
• Time Spent Downloading a Page vs. Number of Pages Crawled Daily: monitor for any fluctuations. A decline in download speed may negatively impact the daily crawl rate.
• Sitemap Categorization: more of a strategy than a tool, however for large sites consider creating multiple sitemaps categorized by site section. This will facilitate the diagnostics process by isolating problem areas (“wow there are a lot of errors in the Reviews sitemap, maybe I should focus on cleaning this section up”) and save a ton of time by not having to troll though thousands of URLs searching for patterns.

However, Google can easily step their game up with improved functionality and features beyond what the redesign is reportedly bringing.