Very Confused - Do I NoIndex Tags Or Categories

Whenever you ask this question about whether to no-index your category pages and tag archives. You will surely get 2 kinda reply, some will say to index and some will ask you to add no-index. Every single forum and every single thread about this issue, you will find contradicting replies.

I was extremely confused before now have come to my own conclusions and it works.

1.Honestly though, you want Google to crawl your tag archives, or it has no other purpose than improving site navigation. But you need to keep in mind that you need to have only excerpts in the tag archives. If you are having full post on the archives pages its gonna be bad(duplicate content). EXCERPTS are must for tags and category pages if you want Google to index em.

2. Don't add too much tags, it will surely piss Google. My general rule of thumb is 3 to 4. Reusing tags for multiple posts is also recommended. For instance, if this a wordpress post, i will be adding tags like 'no-index tags wordpress','no-index categories wordpress','configure all in one seo plugin'. Or stuff like that, don't add more by mixing the words around, take a few more seconds while writing a post and come up with tags that makes sense.(Experts forgive me, i'm writing this for noobs, so have to be detailed).

3. Categories: If you want to index Categories you need to keep an important thing in mind. See, how much categories you have and how much sub-categories you have.
Say if i have a category called Automobile and a sub category called bikes. If i post any thing is 'bikes'. It will also show in Automobile category page. So if you have lot of sub categories under every primary category, you don't want Google to crawl. So it all comes down to how much categories you have and how the category hierarchy is.

On a side note, i do add no-index to a pages like the general archives(Date based) and author pages, login page.

Hope this helps.

Peace.