If the office space market is flush with vacancies those landlords have probably paid for advertising in many different places so it will be easier to find office space on your own. However if the office rental market is tight and there are not many available vacancies, landlords won't spend as much on advertising and finding office space on your own will be tough.
There are companies like Austin Tenant Advisors that can help you find office space however if you are adamant about doing so on your own below are a few tips.
Ask for help from personal contacts
Some of your best opportunities in business come by word of mouth. The same can go for finding office space. Ask your friends and other business contacts that you have if they know of any available office space in their buildings or others. Don't be afraid to ask business owners who lease space in a particular part of town or office building that may interest you.
Ask your lawyer, accountant, bookkeeper or insurance broker if they know of any good office space coming available. If you are a member of any associations such as Chamber of Commerce or trade organization spread the word that you are looking for office space to lease.
Drive or Walk around your desired areas
Spend some time driving or walking around your desired areas. Look inside the buildings to make sure you like them. Keep an eye out for commercial real estate signs advertising office space for lease. Ask people or businesses in the building if they have heard of any available space coming up. Driving around also gives you an opportunity to check out traffic patterns in the area.
Call landlords or property managers directly
If space is in high demand you may need to call the landlords or property managers directly to find out what spaces are likely to become available in the coming months.
Check the internet
You can do a search on the internet to find available office space for lease however be careful with this. Online listings are almost always NOT correct and they don't typically share all the info you need to ensure it meets your needs (e.g. budget, layout, etc…). If you find something you like call to confirm that the info listed is accurate.