Get in some jabs early
The jab is not the most powerful move in boxing, but it is highly effective. When you start your match, try getting in a few jabs and get your opponents health trickled down right away. There's never anything wrong with giving yourself an early advantage and this is a good way to do it.
After getting in the jabs, try dodging a bit, as your opponent will likely try and go for some quick blows on you. Once you see an opening, get in a few more jabs and dodge again. Or, you can go for some jabs and get in a more powerful blow before blocking/dodging again.
Again, these might not be the coolest punches, but they are very smooth, and can really toy with your opponent. Of course, you want to make sure to get a few big shots in there too (which we'll discuss in a bit) but a good jab can ignite a devastating combo.
Practice your haymakers
A haymaker is the most dangerous and satisfying punch you can execute in Real Boxing 2. They are easy to do, but they are tricky to hit. It kind of depends on the boxer you're going against. If you're going up versus a fighter who's very aggressive, then it can be a challenge.
That said, with a little practice, you will be able to nail most of your haymakers. It's all about finding the perfect window of opportunity to execute. Get a few shots in, dodge and block, and then go for the big one. It's a great way to finish off a combo if you can pull it off.
Many fighters will have a tendency to guard their faces, so it could be good to mentally prepare yourself for body haymakers. Nothing wrong with attempting headshots too, but just be wary of your opponent's tendencies as best you can. Time your shots right, and you'll be sending your man to the canvas.
Train your boxer
This goes without saying, but make sure to level up your fighter every opportunity you get. It can be easy to pass up sometimes and go straight into another bout. But always try to make yourself stronger. Depending on what kind of boxer you created, upgrade what you feel is best.
If you're a strength build for example, do you want to upgrade that ability and make the most powerful attribute stronger? Or perhaps you want to strengthen a weakness such as speed. It's all up to you of course, and either way, you couldn't go wrong.
However, if you feel like you're really weak in a certain area, then definitely boost it up. One no-brainer is health. Definitely get that up, especially if you didn't choose that build in the beginning. You'll need XP to pay for the upgrades. If you have diamonds, then you can use those too. Diamonds can be earned as rewards or by purchasing them with real money. You should have a nice chunk of XP after just a few fights, so go wild with the upgrades, champ.