Down Payment
The first part of equity is your down payment. The higher the down payment, the more equity you start with.
Principal paid
Each month you make mortgage payments, part of it is interest payments and the rest are principal payments. The more payments you make the more principal you pay off, thus raising your equity in the property. You can also make extra principal payments monthly or even yearly to build more equity.
Appreciation
Appreciation is the amount that your home increases in value. While the other 2 methods can be planned for, appreciation is not that set in stone. The average appreciation rate over the course of American history says homes appreciate at about 3.5% per year but that can vary based on many different aspects including your location, market condition and time.