Wait for a handle to form. The handle often takes the form of a sideways or descending channel or a triangle. Buy when the price breaks above the top of the channel or triangle. When the price moves out of the handle, the pattern is considered complete, and the price is expected to rise.
While the price is expected to rise, that doesn't mean it will. The price could rise a little and then fall, it could move sideways, or it could fall right after entry. For this reason, a stop-loss is needed.