There's 4 things I look for in a campaign setting in no particular order:
1. Definitely make it an interesting concept. If you can't sell the setting in a couple sentences, you won't be able to sell it at all.
2. Portability - I want to be able to loot it right now for the campaign I'm in the middle of.
3. Also, see about getting artwork that really defines it. Personally, I'm more interested in fewer, but better pieces, than a lot of mediocre ones. And the artwork can really help sell the mood of the setting.
4. And, for me, probably what sells me the most is adventure ideas. If I read your setting and can't stop coming up with more adventure ideas than I could possibly use, I'll definitey use it.
Furthermore, if you want to take a risk and be counter-intuitive - release the setting for free and charge for the supplments. Or probably better yet, release a free, but substantial, "Player's Guide" and charge for the full DM Guide and supplments. You can get far deeper impact in the market with a free setting than one with a price. Without people picking up the setting, the supplements will never sell. Just make it clear that it's a professional endeavor and not just a fan boy releasing his setting. Free products can easily get an aura of low quality. However, this is a gamble and goes against the business model of nearly every RPG publisher before. They believe (wth decent evidence) that supplements are just there to boost sales of the core setting book. Which, if you are WotC that is definitely true. If you are Joe Random Publisher, I think the story is very different and pretty much no one (or very few) have caught onto that. But that's just my theory with little evidence behind it.
1. Definitely make it an interesting concept. If you can't sell the setting in a couple sentences, you won't be able to sell it at all.
2. Portability - I want to be able to loot it right now for the campaign I'm in the middle of.
3. Also, see about getting artwork that really defines it. Personally, I'm more interested in fewer, but better pieces, than a lot of mediocre ones. And the artwork can really help sell the mood of the setting.
4. And, for me, probably what sells me the most is adventure ideas. If I read your setting and can't stop coming up with more adventure ideas than I could possibly use, I'll definitey use it.
Furthermore, if you want to take a risk and be counter-intuitive - release the setting for free and charge for the supplments. Or probably better yet, release a free, but substantial, "Player's Guide" and charge for the full DM Guide and supplments. You can get far deeper impact in the market with a free setting than one with a price. Without people picking up the setting, the supplements will never sell. Just make it clear that it's a professional endeavor and not just a fan boy releasing his setting. Free products can easily get an aura of low quality. However, this is a gamble and goes against the business model of nearly every RPG publisher before. They believe (wth decent evidence) that supplements are just there to boost sales of the core setting book. Which, if you are WotC that is definitely true. If you are Joe Random Publisher, I think the story is very different and pretty much no one (or very few) have caught onto that. But that's just my theory with little evidence behind it.