Keep it relevant. When you are trying to create the perfect title tag you always include information that your target audience might be searching for. Relevancy will not only help the search engine find out where to place your site but it will also help the user decide if you website is in their interest.
Title tags are not restricted to characters but they are limited to pixel length. Always make sure that it fits before you go ahead and hit publish. A half decent estimate is 56 characters. Remember relevancy is key so use those 56 characters wisely. That’s less than half of what you get on Twitter.
Commonly keywords are separated by commas (,) pipes (|) and dashes (-)
We advise using pipes because the take minimal pixel width but are clear separators.
What to avoid?
Google doesn't want to see words like “Home’ and “Product Page” and when have you ever used these words in a search engine? Think about it for your users point of view. It is statistically proven that title tags using these sorts of phrases have a much lower click through rate.
Random capitalisation of word can also put users off your site. It can look a bit on the spammy side. Overly long title tags that are cut off have the same effect. It looks a bit messy and users can think that the website has been thrown up in a hurry. Stuffing every last keyword you know is a bad idea too. Not only does it look like a dog's dinner Google comprehends semantic variations so there is no benefit. Keep your keywords clear and concise.
Avoid duplication. Try to avoid using repeated keywords across the different pages of your site. If ecommerce is your game and have a numerous products on your site then uses data driven titles that ill automatically pull data like product names and categories into title tags through management content systems.
If you don't follow some of this advice then you may find Google will re-write your title tags. That doesn't mean you can stick the kettle on and put your feet up Google’s title tags won't be great. You’ll benefit more if you take the time to do them yourself.