To unlock The Real Deal trophy in Red Dead Online, you need to be the most valuable player in a Series event three times. It doesn't have to be consecutive rounds.
If you're a good shooter this won't be a problem to achieve in a Showdown Series, but if you aren't too hot with the shooting mechanics you can take advantage of the fact that there are MVPs in the Race Series as well. It seems that the MVP is always awarded to the race winner though there may be some rare circumstances where this isn't the case.
There are two modes here: Race and Open Race. While you may be able to win a round of Race, in which you can pick up boosts and weapons along a point-to-point route, the problem is that once someone gets ahead of you it's hard to catch up. Your best chance is in the Open Race, in which you need to pick up all of the checkpoints in a large area -- but you can collect them in any order. Get a lay of the land and aim to collect the "outer" checkpoints in a wide circle before spiralling in to the checkpoints near the centre of the map. The reason for this is that you will need to race to a finishing square after collecting your last checkpoint, and this is almost always near the centre of the map.
I found that the Tumbleweed map was the easiest to consistently win. From the starting point turn your horse immediately left and get the nearest checkpoint, then 180 and head for the furthest checkpoints to the right of your starting point. From here you should head uphill and work your way around the outskirts anti-clockwise, until you get to a sharp bend left and down hill into town. From here it should be fairly obvious how to mop up the remaining inner checkpoints.
Keep trying and learning the routes; at this early stage of the Beta you will likely find that the majority of other players are either unfamiliar with the mode (or horse riding in general) or they are rubber-banding at the starting line by walking their horses in circles, presumably in an effort to level up while they idle. Because of these two factors this trophy is currently a lot easier than it perhaps will be when the idlers disappear and the more skilled players take to the tracks.