Ensure your property is clean, in good decor and well maintained so it gives a good impression when prospective tenants view it. That includes any garden too. Don’t leave rubbish or old furniture lying around, clear it up. Also:

• Reduce the rent: if you can't let your property at the price you want, then try reducing the rent
• Be less picky: for example, if you've asked for non-smokers or no pets then re-consider this. A good local cleaning company should be able to get rid of any smells quite easily and relatively cheaply. It’s infinitely better to have a property rented to a smoker or pet owner, than to have it empty earning no income.
• Furnish or part-furnish the property: this doesn’t need to be expensive furniture but should be in good condition and meet all fire regulations. It’s not a guarantee that the place will attract tenants but consider this if you’re getting calls rejecting the property because it's unfurnished.