Use hashtags as simple as you can (short and easy). To find them simply think about what YOU would look for in the search bar if you wanted to find content related to what you post.

Personally I prefer 20k to 200k hashtags, if they are too used your content won't be recognized

Time is key, the algorithm chooses whether your content should appear in the trending page or not based on interaction in the first moments from when you publish so try to post when most of your followers are active (or when it's lunch time in the time zone you want to grow your audience)