Regular and frequent visits by the crawler is the first sign that your site appeals to Google. Thus the most efficient way to get frequent and deep crawls is to develop a website that search engines see as important and valuable.
Note that you can’t force Googlebot to visit you more often – what you can do is to invite it to come. Possible measures to take to increase the crawl rate may include:
- Update your content often and regularly (and ping Google once you do) – well, an obvious one, so not much to describe here; in a word, try to add new unique content as often as you can afford and do it regularly (3 times a week can be the best solution if you can’t update your site daily and are looking for the optimal update rate).
- Make sure your server works correctly: mind the uptime and Google Webmaster tools reports of the unreached pages. Two tools I can recommend here are Pingdom and Mon.itor.us.
- Mind your page load time: note that the crawl works on a budget – if it spends too much time crawling your huge images or PDFs, there will be no time left to visit your other pages.
- Check the site internal link structure: make sure there is no duplicate content returned via different URLs: again, the more time the crawler spends figuring your duplicate content, the fewer useful and unique pages it will manage to visit.
- Get more back links from regularly crawled sites.
- Adjust the crawl speed via Google Webmaster tools.
- Add a sitemap (though it’s up for a debate whether the sitemap can help with crawling and indexing issues, many webmasters report they have seen increased crawl rate after adding it).
- Make sure your server returns the correct header response. Does it handle your error pages properly? Don’t make the bot figure out what has happened: explain it clearly.
- Make sure you have unique title and meta tags for each of your pages.
- Monitor Google crawl rate for your site and see what works and what not