How Long Should a Meta Title Be in Length?
Generally, a title should be long enough to be clear; short enough to avoid being "truncated."
Truncation happens when a title is too long. Search engine robots will only read so many characters then move on. Different search engines read different numbers of characters but if you keep your titles less than 75 characters you will keep most major search engine robots happy (Google sometimes seems to stop about as few as 70 characters.)
Examples of "Bad" Meta Titles
The following example meta titles are too vague and do not give either robots or site readers enough information:
E-Z Tax Tips
Examples of Good Meta Titles
Tips on Growing Flowers, How to Grow Flowers
2008 US Population Statistics, Number of People In United States
Chocolate Dessert Recipe, Best Baked Chocolate Recipes
Tax Advice, Tips on How to Pay Less Taxes
Note that the above title tags accomplish three things:
They help robots understand what is most important about the content on the page by repeating part of the keyword phrases that would be found in article titles and content;
They make sense to people reading them; and
By using different words meaning the same or similar things without actually repeating them (spam) and using plurals when sensible, it allows for greater possibilities for appearing in searches for the same information but on different terms.
Tips on How to Create Powerful Meta Titles
When creating meta titles:
Do repeat keyword ideas in different words - no more than twice is usually best;
Do tie these phrases to your content and other meta data;
Do use plurals and word variations when possible;
Do limit the use of punctuation; and
Do use initial caps throughout the title.