Because I don't want to write SEO philosophy let's begin with useful tips when optimizing meta title tags:
1. Put targeted keywords in meta title tag
Keywords are what people search and what google ranks for. So, you need to have targeted keywords in your title tag. But be careful, do not repeat keywors. That could look like spamming
2. Match your title tag with H1, meta description and content
As H1 is a very important on-page SEO factor, matching this two factors will give you a boost on SERPs. Meta desciription has no SEO weight but will increace your CTR. If you want Google to show your meta description in search results and not some text that is found on the page, then put your keyphrases from meta title in it! The same is important for content of the page. If your title tag shows what is the page about, then your content need to prove that!
3. Put important keyords at the beginning
Closer to the beginning the better google positions you will have for your keywords. Naturally, if something is at the end, that means that it is less worthy.
4. Keep title tags unique
Keep them unique, at least 50% of title tag should be unique. Title tags that are almost the same on every page is like a book with the same headings for different topics.
5. Keep it short
It is good to be no more than 75 characters but if you cannot make your title tag shorter than that, do not try to go over 120. The longer your title tag is the less percentage your keywords will have.
6. Make it sound attractive
Title tag will be shown on SERPs so you need your title tag to be attractive. Impressive title tag will just call people to click on it!
7. Put your brand in title tag
People like when something is branded. Maybe your brand is not famous but that will improve confidence and trust. People will see someone who represents what that page has to offer. A good place for brand would be at the end of title tag.
8. Put your Geolocation in title tag
Many searches will have location included so it is good to take advantage of that. Of course, if location has no importance for your business then you dont need to follow this step.
9. Think about singular and plural
It is not the same and you should think to cover both types of searches. In future this will may be worthless if google becomes smarter and find out that something is the same, but for now you should consider that.
10. Suggest in a comment ;)
If you think that I mmissed something, leave a comment and give a suggestion!
If you follow all the 10 tips I described, your overal SEO performance should be much better!