How can I promote my products for FREE?

You are just starting so it's going to take time, especially
if you aren't doing Amazon Ads.

Keep making more notebooks, try additional social media
marketing like Pinterest and anything else you have not
tried already.

Start publishing things with content, as low content is
saturated. Use A.I. for text and illustrations.

And if you haven't already done so, branch out to other
print on demand platforms and products such as mugs
and clothing items, so that you aren't relying on just
one income stream.

Use social media platforms like Facebook and Instagram and you can also explore using YouTube by creating content around your products and drive traffic.

I would forget about sales and marketing techniques and how great your product is or how great it is and actually focus on not on ads and things like that, but focus on people and how you can help them, the best way for connecting with people is facebook messenger and not talk about you, talk about them put to one side the money and sales aspect, and just speak to them as a human being, speak about general things and when the realtionship is built share your business when it feels naturally to do this that you are recommended this to them as a friend and they will trust a friend and you are providing a solution rather than doing what everyelse does just pitches a product every 5 mins, this is what i believe give value value value and then sell once in a while, i hope this helps you

Blogging you tubing list building ,a funnel and or a face book fan page to help boost your reach and engagement .

You cannot promote your products for free. Your social media pages will take time to grow. Keep posting your new designs and your customer reviews with the same Hashtags. The hashtag is a game changer. I hope my reply will help you out in your journey.

The short answer here... TRY MORE.

Im going to assume you have a 9 to 5 type job? and then lets account for travel time so 8 to 6? what are you doing from 6 to midnight?

Contrary to the whole 4 hour work week ideas you see running around - you are going to have to GRIND this out.

There are 2 variables in life; TIME and MONEY... if you dont have the TIME, you had better have MONEY; and if you dont have MONEY, you simply have to put in the TIME.

I suspect you are trying to target people with the whimsical titles of the diary. I suggest some research on say Youtube in regards to the end uses of a diary. Would also suggest adding Diaries with blank pages.

Do the research to determine WHO uses a diary, and then start targeting those specific markets. some examples

Makers of all types ( woodworkers metal, crafts etc )
Fashion designer types
Architects
Construction
IT
Artists
Entrepreneurs

There are MANY end uses, and you are specializing to cutesy cutesy - start targeting specifically to a more focused set of groups.

With this your Social media efforts can be far more hashtag driven with greater reach and greater targeting which should result in greater success.

2 yrs of lack luster results might be time to think this over... months? your just starting and need moe time PATIENCE is a thing - but patiently waiting with out actively trying to grab attention is a path to failure.

Since, it is starting phase of promoting products, you will face struggle but don't lose hope. Try to engage audience through other social bookmarking sites like Pinterest,
plurk, you can also do microblogging, Image sharing or even guest posting on a website that has millions of users. You will definitely see some growth for promoting your product.

what is your niche first diagnose the market solution then focus on target market