All returns paid to investors are determined by the share class they are buying when investing in your company.
If you are issuing Common Shares, there are no guarantees of returns, and you must be careful not to promise any returns from your campaign. While you believe in your company, from the eyes of the regulators, your company is small and high risk. You must be careful not to mislead investors when inviting them to participate.
Common shareholders will often hope to receive return either through the sale of the company, the company going public, or the company issuing dividends (payment of some of the annual profits to shareholders).
If you are issuing Preferred Shares which carry specific rights to annual dividends, then you are promising to pay investors a certain amount each year.
While this places greater pressure on the company to generate enough money each year to pay the dividend requirements, these dividend payments can make the shares, and by extension the investment, more appealing to investors.
Talk to your lawyer about the implications of issuing either type of share.
Companies raising on Equivesto often issuing common shares, which carry fewer obligations to the investors than preferred shares.