It can be difficult to overcome a previous judgement error. An overstay of 10 days from 8 years ago may be harsh, but reflects the growing public mood in Europe towards visa abuse.
Fortunately there are at least two good ways to overcome a pejorative visa history...
The first, and better alternative, is to build up a record of successful performance in countries that monitor and punish overstayers. These countries would include (but not limited to) the USA, Canada, Brazil, Japan, Russia, and the UK. Having a strong record of compliance is a compelling reason for an immigration official to decide in your favour. Although it is a self-referencing rule because it leaves the person in an initial quandary about where to start, it is arguably the best way to effect a permanent cure to clearing up one's overstay history. Three or four compliant journeys is usually enough, but more is always better.
The second alternative is to have a compelling change of circumstances such that the prevailing conditions that made you overstay the first time no longer exist. This strategy requires a solid understanding of rules along with the ability to depict the change in circumstances in a logical and disciplined manner. Persuasive writing skills are key. Accordingly, this alternative works best when using a lawyer who has built up a practice area helping overstayers.
Although your question is scoped to visiting, you may want to try one of the family routes. For Denmark it means posting collateral and a rigorous language hurdle that you may find unpalatable. More info here. There are also some protected routes under Article 8.
Given that you have an in-country refusal and two out-of-country refusals in your history, I would recommend not attempting another application until you have one of the above strategies firmly in hand. Although the literature states that each application is a unique event governed on its own merits, a lengthy series of refusals can be an indication that you do not understand the rules. This can create credibility issues in its own right.