GEDmatch is a free site full of tools.
Gedcoms are filled with trees.
WikiTree works the magic and makes one huge tree grow.
To use the tool on GEDmatch called Gedcom + DNA you simply enter your kit number and it will produce all the people who have trees that match your DNA. (You still have to search for your common ancestor.)
If you upload your Gedcom (tree) you can then perform a "compare one Gedcom to all" and it will search all of the Gedcoms in the entire database (whether you share DNA or not) and provide a list of possible common ancestors you share. It gives you close date, time, spelling comparison so it can take awhile if you have a big tree.
This one tool alone is a good reason to upload a Gedcom directly to GEDmatch and also have one at WikiTree.
On WikiTree you can post your DNA verification (Y, mtDNA, and atDNA) and GEDmatch Kit number to your profile and your entire tree and all names connected to your tree will populate with your kit number. Others can then test against the profiles in your tree.
If you haven't yet compared your GEDmatch kit number to everyone on WikiTree's Brady DNA list (or any other surname list want), please do so. Just type in the surname Brady (or other) which will take you to a list of ALL of the Brady (or other) surname on WikiTree.
At the top of that surname list page are pull-down menus. Choose the one that says DNA connections.
This provides a list of every Brady (or other surname) who have taken some sort of DNA test. Click on their profile, there is a direct link back to Gedmatch so you can do a one to one comparison with that person's kit number.
Check against everyone in the entire surname DNA list. You may find a cousin. That's how I found Paul.
Yes, it is time-consuming AND FUN!
It's like hunting for gold with a metal detector, you can't rush it.
After you do about 50 for several of your surnames, (you get a rhythm going) it is a blast when you get a match. You will increase your speed too.
Playing the piano takes practice; so does playing genealogy.