Remember that you can`t reinvent the wheel, but you can come up with new ways to use it. Just because some of your ideas are already present doesn`t mean that you can`t put a new spin on them to reach a market that current providers aren`t.
For me, engraving isn`t a new field, but I concentrate on niche`s that tend not to get marketed to. I come up with niche specific ideas for those markets.
Research what is out there and you will find that there are always areas for improvement.