Updated on Mar 13, 2019
Title tag should contain your target keyword - The title tag is quite important to the SEO and should contain your exact target keyword.
Title tag should begin with the exact target keyword - this is a nice addition to the previous point. However, a target keyword placed anywhere in the title tag will also do its job right.
Title tag has 55 characters or less - Google only shows the first 55 characters of your title tag, so using longer title tags won't give you any benefits whatsoever.
Description tag has 155 characters or less - the same principle from the title tag also applies here this time though, the amount of characters is upped to 155.
Description tag includes exact keyword - As you know, when you search something on Google, when a match has been found the keyword will become bolded in the description. Use this information to increase your Click through rate and improve the SEO of the page.