Yes, you can conduct patent search by yourself at free and paid patent databases. However, you have to understand patent database search operators and syntax to conduct exhaustive keyword search.

Also, you may not have access to paid patent database. So, you have to limit yourself to do patent search only in free patent databases. However, it is advisable to get a patent search done by a professional patent analyst. Patent analyst conducts patent search (including keyword and patent classification search) especially in paid databases which may be exhaustive in general, compare to patent search done by yourself in free databases.