Watching Your OpponentAlways keep track of what your opponent does. As a beginner, you don't want to start making mispredictions right off the bat. Play normally, and just keep track of what your opponent does. What switches did they make? What kind of moves did they go for? As you record what your opponent does, you can start playing more aggressively. People tend to repeat the action that feels comfortable for them. Once you know what they like to do, you can start turning it against them.
Applying Prior KnowledgeThe key to learning is memory. If you battle a lot, you'll see some of the same moves between different players. It's not that they're copying, it's just the better move to make. If you remember what others have done against you often, odds are your current opponent will do it, too.
Not only that, but remembering a Pokemon's set will also help. While these aren't so much predictions, they are still going to give you an advantage in battle. Knowing your opponent's set will put you in a higher position of the battle, because you then know how to play against it.
Of course, some Pokemon are somewhat unpredictable. Many OU Pokemon just have many sets and roles. But, fortunately, because of those roles, they will only switch in at certain times. Why else would a Tyranitar switch into a Skarmory or Gliscor? It has a move that can take it out. Either that, or it's bluffing (which is usually rare in Pokemon battles unless the Pokemon is U-Turning). But most likely it's a threat to your Pokemon and if you don't keep yours safe, you're going to be pounded.
The Most Profitable MoveA lot of thinking goes into this one, but this goes for both sides: there will often be times where more than one move is good. But, there is always a better option. That is the move you want to go for, the one that rewards you most.
But then there's also your opponent's best move. What would be best for them? Factoring in that, your best move may not be the same anymore. You have to consider what your opponent's best move will be, as they will probably go for it. You find out that move, and then you can throw it against them yet again.
Of course, that's IF your best move changes. It most likely will not, because your best move is the move that will most likely put you in a good position. If you are to play your opponent's best move against them, most likely they'll still have the advantage.
OverpredictingThis one's a bit controversial. It was created by the idea of just thinking too far ahead, and some say that it's just misprediction with a fancy name. Either way, it's bad to do. Pokemon is similar to chess in that it has very complex strategies, but it is not chess. It's not favorable to look so far ahead into a match. If you're indecisive about a move, stop thinking so much about it. Sometimes you just need to go for a move. If you always think ahead, you're likely to lose at some point. Most of the time just think about the present; future moves can be worried about later. You'll most likely face people who don't predict at all, and you don't want to try and guess moves that they'll never make. This goes with the first section; watch your opponent, find out how they play.
Of course, as you play more, you'll start to ease into predicting. Experience is great to have, as you can constantly apply what you've seen before. You'll also learn how to think quicker, and being able to think fast is very useful in matches, considering many official matches impose time limits. The only thing about predicting is that in OU, it constantly changes. So you'll have to forget some old strategies and start applying the new ones. Just be prepared to constantly learn, because you can't predict without learning.