The process starts with a trademark search. It is optional but oftentimes recommended. I offer two types of searches. The first is a limited trademark search which searches both federal and state databases for other marks that might be similar to your mark. If there is a conflicting mark, then this means that you will not be able to get a trademark for your proposed mark. Plus, if you do proceed with adoption and use of your proposed mark, then you may be infringing on their mark. The second is a complete search which searches more databases and give you more peace of mind.
The limited search which costs $750 searches federal and state databases. The complete search which costs $1500 searches federal and state databases but also searches a number of other databases such as domain names, magazines, Dun and Bradstreet, etc. Hence, the greater peace of mind.
Alternatively, you may forego the search step and proceed directly to the trademark application filing step. The United States Patent and Trademark Office performs their own search after submission of a trademark application. However, the search is that of only the federal trademark database. The cost to file a trademark application (word mark, single class) is $700 including the governmental filing fee.
If everything goes well, you should have a federally registered trademark in about 6-9 months.