First be clear, I try not to recommend fast fixes too often to my students. Often, when you try a fast fix, you are adding a fault to your swing. To fix a fault, perhaps in the short term, your shot is better, but nearly always you will create more problems for the future. This being said, I understand that sometimes you are on the course and struggling with a problem. It is destroying your enjoyment of the game or the match you are playing in, and you need something to get you home and keep you in the game. Or perhaps you on the range before you play, and for example, you cannot stop slicing. You need a fast fix for the game coming. These situations are what I can help you with in this article, but please keep in mind, these are not meant to be long term fixes, and even if they do help with you with your problem, I would always recommend after your game to go and have a lesson and find out the real cause of the problem.
The Slice
First of all, you need to understand the basic fault that is causing the slice – your clubface is open relative to your swing path at impact – Swing path left – clubface right. When you are looking for a fast fix, you are trying to find the easiest way of achieving what you need. 
In this situation, that would be a swing path more to the right and a clubface more to the left. Because if you can do this, you will fix your slice on the very next shot.
Swing Path Fix
Take a look at the picture from above the ball on the target line.
You can see that the club swings around your body and through impact on a circular path. From this, it is easy to see that the further the ball is positioned to the right in this impact zone, 
the easier it will be to create a swing path to the right of the target. This is your swing path fix. Place the ball more to the right in your stance – how much will depend upon how big your slice is. I would also like you to try and swing to the right of the target through the impact zone.
Clubface Fix
From my experience, if you fix your swing path, there is a good chance that will cure your slice alone. Most slices are a swing path fault, rather than a clubface fault. 
However, if your ball is still slicing, try the quick fix of turning your hands more to the right on the grip at address, and turning your hands more to the left through impact. This will be sure to have your clubface pointing more to the left at impact.
The Hook
Again, like with the slice, think what the cause of the hook is. Your clubface is closed relative to the swing path at impact – Swing path right clubface left. If you can make your swing path more to the left, and clubface more to the right, you will fix your hook on the very next shot.
Swing Path Fix
Like with the slice, if you look at the picture from above the ball on the target line, you can see that the further the ball is positioned to the left in this impact zone, the easier it will be to create a swing path to the left of the target. This is your swing path fix. Place the ball more to the left in your stance – how much will depend upon how big your hook is. Also, opposite to the slice, try and swing to the left of the target through the impact zone.
Clubface Fix
Again, if you fix your swing path, there is a good chance that will cure your hook. Swing path faults are normally the main cause of slice and hooks, but if your ball is still hooking, try the opposite of the slice. Turn your hands a little more to the left on the grip at address, and through the impact zone, try keeping them as passive as possible. This will be sure to have your clubface pointing more to the right at impact.
Heavy/Thin Shots
So, what is the cause of heavy and thin shots? Both these shots are caused by the bottom of your swing being too much to the right side of the ball. If you hit the ground before the ball, you get the heavy shot. If you happen to just miss the ground you will hit too much up at impact and get a thin shot. If you can move the bottom of the swing more to the left, you will fix your heavy and thin shots very quickly.
The Fix
By keeping your chest more centered on the ball during the backswing and downswing, your chances of making impact in the correct position will increase a lot. Make some practice swings placing a small object on the ground, perhaps a coin if you are on the range or a small stick if you are out on the course. During the backswing, try and keep your chest to the left side of this object, with more weight on your left side. In the downswing, focus on striking the ground to the left side of the object. If you can repeat the same movement with a ball, your impact will instantly improve.