All of the advice is mixed up here. First off, you can apply to register a trademark before it is used, if you have the intent to use within a year. It is a different form of registration, and requires a follow up when you do use the mark in trade. You can read about that on the USPTO.
You can do it yourself, and in fact it can now be done electronically on the USPTO web site for cheaper. But the process is GIGO: you can try to trademark anything not currently in the database, but any other prior competitive use could challenge your attempt to register your mark. Registering your mark does not guarantee anything, it is just one more way to protect your mark. You don't have to register your mark to protect it, just protect it. In fact, even if you register your mark, if you don't protect it, you can lose your rights to it. How to protect it? The first thing is to use it in public and indicate it is your intent to treat as a protected trademark by including "TM" with its use, or words indicating it is a protected trademark. You don't ever have to register to do that. If you register successfully, you replace the "TM" with the "circled R".
It is up to you to do searches to see if there are competitive uses. The USPTO will do this as part of the registration review, but if they find a competitive use before you do, then you are out your registration fee when they refuse you. So, do your homework. These searches are in part what you pay an IP service for.
If you want some help at not too much cost above the registration cost, check out trademarkia.com for registration service. They act as your filing agent and legal representative. They also search their own reasonably large database of marks for possible competitors.
I did my first one through trademarkia, and once I felt comfortable understanding what they did for me, I did the next on my own. I did word marks for names of my spirits. I plan on doing design marks in the future.
In the end, though, if you plan to have trademarks, you do need to be ready to consult with an attorney, because protecting a trademark really means that you are willing to legally defend your use from others. Unless you plan to defend yourself without a lawyer.