help - gmail - 197% space used - I will delete all email with "unsubscribe"?

[InGearX]

in very short:

what are some good ways for me to reduce space in my gmail?

* I can buy 100GB for $2 a month .. but I would rather not waste disk space / resources ..

* I used https://www.findbigmail.com/ and it labeled some that are above 1MB .. above 2MB .. above 5MB .. but I see that I would want to have some for reference later .. hmm I could use a filter on these labels to target ones I really do not need .. hmm how?

* or any other like sites / services?

* I could also "save" specific emails by forwarding them all to another gmail account and then deleting them from this one ?

* so it hit me - why don't I delete all emails with keyword "unsubscribe" in them .. hmm what do you think? would I be safe to do so? (I imag

* hmm are there any other alike keywords I could use?

* any sites describing best practice / tips / tricks?

thank you ..

in details:

hmmm I just got a notice bar on top of my gmail:

You’re out of storage space and will soon be unable to send or receive emails until you free up space or purchase additional storage.

I look on the bottom and to my surprise it says:

31.54 GB (197%) of 16 GB used

WOW

I go to

https://www.google.com/settings/storage?hl=en

and I see:

31.53 GB used

Drive 0.1 GB
Gmail 23.38 GB
Google+ Photos 8.04 GB