Impact investors are not all the same. They can be broadly broken down into two groups: impact-first investors and financial-first impact investors.
The financial-first impact investors often seek to achieve market-rate returns on their investment, and are not willing to compromise on this expectation. They still maintain an interest in impact, however, and thus can be important partners in achieving both financial and impact results.
Impact-first investors are open to receiving lower financial returns, and often have a more patient approach to investing. Please note that there is by far more financial-first impact investment capital available in the market at the moment.

If it is an equity investor or an investor with major investor rights, it is like a marriage. After closing the investment, the investor becomes part of the decision making of the enterprise. If this is the first time investors are involved it is a major shift in the governance of the organisation. Consider them as part of the management team and not only as financiers. And this is not a bad thing per se – they have a strong interest in the organisation developing well.
Of course, it is essential that investors share the overall vision of the management team. Therefore, you should explicitly address the mission alignment before any engagement with new investors. 

The whole organisation should be ready to take off! Are you just waiting for the necessary capital to make your plans happen? Well, investors should exactly get this impression. To convince them, you’ll need to meet some industry standards in term of preparation:

• the business plan has to be ready and easy to follow
• the impact assessment and monitoring system should be in place and well documented
• the company governance and organisation has to be ready for growth
• you meet formal requirements in accounting and reporting (e.g. audited accounts)