Double against the dealer's 5 or 6, otherwise hit. This hand is one of the worst you can be dealt, but the fact that this is a soft hand leaves you a chance to hit. Cards like 5-7, and 8 for a 13 hand will improve your situation.
On a hand of soft 15 and 16 double against the dealer's 4-6. You should never stand on this hand as you cannot go bust by hitting. By doubling you are betting more and thus can win much more.
Double on soft 17 against the dealer's 3-6, otherwise hit. In case the dealer's up card is 3-6 he has a good chance to go bust, therefore we advise you to double the bet and thus win more.
Double on soft 18 if the dealer shows 3-6. You may be surprised with this advice, but according to statistics, this hand wins if you stand 58% of the time, while if doubled its 55%. However, you can win much more money when doubling as you double the original bet.
Stand on soft 18 against the dealer's 2-8. This is the best moment not to risk anything as you can assume the dealer has 10 in the hole, his hand will be strong. Therefore, do not take the risk.
Hit a soft 18 only if dealer has 9, 10 or an Ace. In this situation you'd better try to improve your hand against potential dealer hand of 19-20.
Always Stand on any soft hand of 19-21. Do not risk this hand no matter what , as you are unlikely to get a hand stronger than this if you hit or double.