How to get traffic from Hacker News smartly?

I mean this in the kindest nicest way possible... you are doing it wrong.

Please worry about solving a problem that once solved reduces human suffering (developer suffering). Once you are there learning how to distribute that solution will be much simpler.

One trick is to write about a blog post about an interesting problem you solved for your site. If you meet a technical friend that you have not seen in a month, and s/he ask if something interesting happened in your site, what would you tell?

One of the problems with free images is that they don't own the images they sell. Are you drawing them? Are you hiring someone in Fiverr? Do you have a problem hiring freelancers? How long does it take to draw one? How do you change the pallete of a graphic if you decide to make it darker or lighter? Do you have chargebacks or credit card fraud?

Assume people here has a technical background, but are not graphic experts [1]. Something that is usual in graphics may be interesting for general public, but not if it only a button in Photoshop.

If your English is not very good, get someone to read and fix it. Or at least write it in MSWord or some editor with orthographic and grammar correction. This is not very important for HN but it's important for the general public.

As an example, you can see the posts of bemmu about his site candyjapan https://news.ycombinator.com/from?site=candyjapan.com

[1] I usually draw in Paintbrush, when it is complicated I use Gimp, and some times Inkscape.

Don't treat HN as some sort of free advertising platform. If you created something you're proud of and you genuinely they can help the community, feel free to post. Otherwise, if your plan is to make a profit, don't bother.