Mostly just dont overthink about it. There are three ways in general:
1. Just score more points. Optimize your own game and you can often pull ahead even though someone gets a good science run
2. Plan ahead so you can play or hide their cards, either resources or green while not sacrificing your own possibilities
3. Just ignore the situation and secure the 2nd place behind the science player. Usually the best option if there is zero awareness or cooperation from the other players in the table.
On some wonders and some situations you can also play a green game, either scoring one set or building a single chain, even if it is not your main focus. Pick carefully and you can limit green player options a lot, since they often have just one particularly good card in that hand. It is better to snatch yourself a 5 point green instead of a 6 point blue, if you are ahead in the game and that green would score a lot more for the green player.
Then again, you can be a green player yourself. 5 or more players and you can make a lot in it even if you have competition. Especially if your wonder is not expected to rush for green, you might catch them by a surprise and pull ahead before they realize what you were up to. Memorize what resources you will need to play efficiently. In early game you can also force yourself to become the main green player and then others need to take another path. This is often risky, but can win you a difficult table setup if you get lucky. Worth a shot if you have a bad starting position and your opening hand does not improve your general situation. You can't win every game.
