When the ball is just off the green there's a decision to be made about what club to use. I always say the first thing you should consider is 'can I putt'? An old saying which still rings true today is that a bad putt is always better than a bad chip. I would approach the green with this mindset. If the grass is quite short I will invariably choose a putter unless you have a bunker to contend with or having to go over hills or depressions.
Now if you have to chip the ball a decision has to be made regarding which club to use. If you take the example of a flat surface, the typical rule is that the SW needs to land 50% of the distance to the hole, PW 40%, 9 Iron 30 % and so on. You could chip with even your 5 iron if the shot permits and you've practiced with this club.
Now choosing between these clubs depends on where the landing area takes place. The general rule is that you would like to land the ball on the green in one shot as landing on the fringe or before can be unpredictable such that it doesn't give you a consistent roll. Therefore if time permits when approaching the green, you could count out the steps to the hole and find out exactly where half way is. This would be the landing area for your SW. You may be able to choose other options as well as long as the landing area is on the green.
Ofcourse if it is an uphill or downhill shot, you would just make the necessary calculations. Also there might be times where it is unavoidable to hit before the green. In these situations check to see where the grass is growing. If it is growing into you, otherwise known as into the grain, you may choose a lower numbered club as you want the ball to roll more effectively through the grass. If the grass is growing away from you then chipping off the green wouldn't really affect your shot. You can check whether the grass is growing into you by doing practice swings and noticing whether the club gets stuck in the grass.
If you would like further help in deciding what chip shots to play, please let me know and we'll organise a time to meet.