As with any career, the first few years are likely the most difficult. It is not easy to conform to working for a big, stable Landscape Design company while expressing and actually utilizing your own distinct style. Smaller firms allow more creative freedom, but are typically not as stable. Establishing your own firm allows the most freedom, but is a lot of work and tough to pull off. It takes years to get enough of the reliable clientele, like property management and those who work with real estate, to sustain a Landscape Design firm.
After a few years, a good Landscape Designer in a big and stable firm either does rather well, or moves on to establish his own Landscape Design firm. By this time, starting a new firm is still a lot of work, but not as risky for a Landscape Designer who has a good reputation and knows to avoid the forbidden fruit.