Kinect Sports

Like in the solution for Bump-osauras, you can utilize your Xbox Guide Button on your controller (off-topic hint, the controller is great for menu navigation too!) This exploit is very helpful for defending.

Defense-
When the CPU has the ball, spend a few seconds trying to stay in front of the attacker. Hit the guide button as soon as the ball path is shown. You may have to anticipate it a little early; I consistently had to hit the button several times so I could be in front of the ball path in time. With the guide button essentially "pausing" the game, you can move to where the ball path is and intercept. If you hit the guide button to late, you may not be able to intercept the ball in time.

Every once in awhile, the ball will get by you, and the CPU will have a scoring chance, They'll wind up to kick, and as soon as there foot hits it, a target will appear showing where it's going. Again, hit the guide button as soon as this target appears. Move your entire body in front of it, as well as both hands, then "un-pause". I let a few goals go because I only reached my hands out, so have your entire body there. Using this method, you should rarely get any shots on your goal, and if you do they should be simple to block.

Offense-
The guide button trick won't really help here. Personally, I'm not very good at Football on any difficulty. However, with a strong defense (as detailed above) you'll have more opportunities to pass and score. On Champion, the defenders act fast so you have to pass fast. I usually passed to the direction that was open, regardless if I had a player there, I felt I had very little time to dribble or plan out my pass. If a teammate is there, great, if not, one will usually run to where the ball is, and if you screw up and the CPU gets it hopefully you can steal it right back.

My tips for shooting is to aim slightly left or right, and give the ball a healthy kick. Kicking too hard or with too much angle will just sail wide or high.

I did this in co-op. It just takes the pressure off as you alternate goes instead of having to do everything yourself, but the premise is still the same.

For me personally rushing didn't work. But don't take too much time either. As your partner is taking their pass you can usually see down field where your blocker is going to be and decide on which direction to kick before you get the ball. don't dawdle. Try to go down the wing and end up in the middle to shoot, as it's very difficult to score from the sides.

When defending lean to one side, and it usually tempts them to aim to the other side. Lifting your foot out is easier and normally sufficient to block, and takes less time than actually stepping over.

When in goal, try where possible to catch the ball by getting both hands to the yellow target circle. It's not always possible, but deflecting it very often gives them another chance to score or a corner.

When shooting you can't take too long or you'll get attacked. You could try to use this to your advantage as it could result in a free-kick or a penalty. Watch where the keeper is, she always just hung around the middle for me and she was a pretty good keeper, but take a second to line it up and aim for one side. They'll drop in eventually.

Don't bother time wasting when you're in the lead. They'll just take the ball off you. Keep pushing for more goals - it feels so much better to be 4-1 up with 20 seconds to go than 1-0 up and panicking they'll get the draw.

Good luck!

I can't give a ton of tips but stay centered to the ball as a goalie and if your quick you should be able to stop most shots.Remember to try and catch the ball with both hands to avoid giving up a rebound. As for scoring goals, hard shots from the center tend to work best. The harder you kick the better chance you'll have of scoring.

In the end, it really comes down to how good of a goalie you are, as the shots are tough to stop and you need to have quick reflexes otherwise you will get scored on a lot.

he key here is possession. The longer you keep the ball without losing it, the less chance the computer has of taking the ball and scoring. When you’re passing the ball around, remember to pass into space. If a player is marked and you pass to them, they will more likely than not, get tackled and you will become subject to a counter-attack. Try and shoot when you feel confident that you’ll get the shot on target, as the more goals you can score, the better. Try and build up a good lead, and if you keep up the offense you may even get “Golden Boots” at the same time. When it comes to defending, make yourself as big as possible as the computers favour passing to the side, not between your legs, and this means you’ll have to move less to block passes. If the computer does get a chance to shoot, try and adopt the stance of a real keeper legs slighty apart and arms at a 90° angle and bear in mind that with it being Champion difficulty, there will be a fair bit of stretching for the tricky corner shots. After the match is finished, if you’ve beaten your opponent, then your Achievement will unlock.

EDIT: Thanks to DVSTEZ
if you get the ball up to the striker as fast as dyou can then shhot instantly it has a 90% chance of going past the keeper