No-one likes to feel they're kept under the thumb. It's amazing what a bit of freedom does for creativity and productivity. So provide your staff with challenging work, clear instructions about time frames and the space to do it their way.
You're in charge of developing your staff and they'll grow if you stretch them with the responsibility of challenging work. All they often need is clear instructions about what's required, what you expect, the time frames involved and the freedom to implement in their own way.
Support staff with regular reviews and frequent, constructive feedback about their progress. To really motivate them, give praise along the way. If a staff member misses a deadline or doesn't deliver, ask what problems were encountered and what support was needed. Then encourage the staff member to get on with the job. You'll see the difference quite quickly in productivity and achievements.