Below are a number of basic game tactics to help you in FIFA 09. You need to have some sort of structure in your play if you expect to win games. You can't just go out and pass around and shoot when ever, you need a planed form of attack and defence.
If you possess the ball, your opponent does not, and therefore he cannot score. By possessing the ball with a series of smart passes, you can run down the clock if you are winning, or wait until you see the killer passing option through to your strikers and play them in on goal. If you can possess the ball and pass well, you don't have to be good at much else to win games in FIFA 09. Most concepts in FIFA are similar to real-life football, just look at how Barcelona play!
In FIFA 09, much more so than nearly any other version of FIFA, speed is much more important than most other attributes. If you have a speedy player with the ball, you should very rarely turn down the chance to run into space. Strength is also important in FIFA 09, so even if your player is fast he may be pushed off the ball, so try to distance your player from stronger ones to avoid letting your run get cut off early. This is especially important down the wing (see below) when your outside midfielders or wingers typically have a lot of space to run at.
Playing with a team that features a quick, pacy winger(s) is incredibly useful. Teams like Manchester United who have Cristiano Ronaldo on their team can create goals solely from utilizing his skill and speed. If you have a winger like this, it is not a bad idea to completely center your play around him, as if you get good at relying so much on your winger, you will realize how useful they can be by making quick runs down the sideline and playing a good cross in. It is a simple technique but considering how important individual pace is in FIFA 09, you'd be dumb not to take advantage of it.
Skill moves are incredibly useful in all versions of FIFA, but players tend to ignore this. Whether it be because they are too hard to get used to or because they don't know just how useful they are, they are truly a hidden tool not to be ignored. Spending the time to get good at skill moves is well worth it, not only will you surprise your opponent by dribbling all over the pitch, you're missing out on a lot of scoring opportunities if you don't know how to use skill moves correctly. Something to consider is that if you want to play the all out skill moves game, look for a team with a lot of players with high dribbling stats.
Although it is very hard to break away from assisted settings and play with full-manual controls, it is well worth it in the end. This is the same concept as mentioned in the skill moves section above; there is a tight learning curve but you'll be upset you didn't make yourself learn it earlier! Imagine if your shots and passes were 100% controlled by you. Of course, you would have no one to blame when you missed, but once you are proficient in manual shooting, you can hit corners consistently and thus score more goals. See more on the Manual vs. Assisted controls debate here.
This one is sort of a given, but set pieces are one of the most useful things in FIFA 09. Because of the importance of strength and physique of a player, more so than previous versions, all set pieces used as a pass are golden scoring opportunities. Free kicks taken as shots are something you should absolutely not ignore. Once you get good you will score maybe 3 out of every 4 attempts, and that's a pretty good ratio, enough to make your opponent think twice about fouling you.
If you have spent any amount of time playing FIFA 09, you may notice that the all-important duo, so to speak, is speed and strength. The best players tend to be strong, quick ones, seemingly regardless of other attributes. Take advantage of this on offense when you are playing with a team who has a big, strong striker such as Fernando Torres of Liverpool or John Carew of Aston Villa. When determining what the best method of attack is, consider giving the ball to a wide player who can make the run down the wing and cross it into your big striker. In terms of heading the ball, and many other things, strength rules all, and if the cross is good your big striker will likely get his head on it and put it away. Also try utilize your strong players when you need to hold up the ball and let play develop.
This isn't really a strategy, but something to consider when trying to play a certain way. Although it is nice to have strategies and ways of playing which work well for you, you may be forced to change it up every once in awhile. Don't always use your wingers, try to posses the ball a bit or immediately try to play your forwards in for a chance to finish. This is especially important if you're playing online because human beings notice patterns better than computers do and will act accordingly.