Hi Mark,
This is a really good question, I definitely think the best way is to firstly focus on your own game, what you do well and how to play to your strengths. Then secondly look at your opponents and how to limit their strengths and finding their weakness in tactical play. It can be easy to focus to much on your opponents and then neglect your own game so thats why I think this way is best.
Of course you need to adjust your game for each opponent and use different tactics but if you can firstly get your strengths going well doing that will be much easier. Many players over think about their opponents and forget they need to play in a style and use tactics which fits your game best.
Hope thats helpful!
Tom
