Will they pay me enough?
It should come as no surprise to you that this one is most important. It's easy to get lost in your business' needs when you're looking for a developer. You have to remember that people don't want to work for your company because they love it, they want to work there because they need to pay their bills. Becoming excited about the company and its mission comes later, after you've built trust with your new employee.
When setting compensation for the role, focus on how much value the person is providing your company. Come up with a number, then look at sites like Glassdoor and AngelList to see what other companies are offering. Don't compare only within your industry or vertical: good developers move fluidly between these, so you're competing with anyone who hires developers, not just those in your industry.
This is a different story if you're looking for a co-founder or most of this person's compensation will be in equity. See this post for more information.
Are there any red flags?
If your company is an organizational mess, you have no experience managing developers, or you don't stand out in some way it's going to be extremely difficult to attract talent. See this post for more info about these problems.
Will this company be around in 2 years?
It's wonderful that you have complete confidence that your company will be a huge success. After all, you wouldn't be working there if you didn't! Potential candidates don't know how awesome your company is, though. In fact, one of the first things they're going to do is assess whether your company will even exist in a couple years.
Don't take it personally — you'd do it too if you were in their shoes. This is actually a feature, not a bug: ask your potential employees to be candid about their concerns. This does two things for you: it gives you an opportunity to address those concerns and opens your eyes to blind spots you or your company may have. You can then be proactive by incorporating this feedback in to company communications and in your candidate pitch.
Do I report to an engineer?
Mid to senior level developers look for this more than juniors. If you aren't already you should have as many developers as possible report to people who are (or were) engineers. This makes everyone's life easier: non-technical stakeholders tend to get frustrated with developers, so having a go-between to translate helps keep things civil.
Is technology the core business?
Developers want to work for companies where technology is the core business and generates the most value. Failing that, it should at least be treated as such. Developers derisively refer to these companies as "tech-enabled" and jobs at them as "cost center" development jobs.
If your company is one of these you'll need to go out of your way to communicate that you value the work your developers do. No one wants to work for a company that doesn't value what they do, and good developers can work anywhere they want. You'll have to work a little harder to sell yourself, but be humble and do it. The stronger talent you'll attract will be worth the effort.
Need a hand?
Want to go more in-depth?
This article is pretty high-level. If you want more details and tactics on how to deal with developers, sign up to get 50% off my upcoming book, Dealing with Developers.