Have a look at our great new tips about counting and never see counting in the same light. It really helps to break down what is happening when a child struggles with counting and ways to overcome this. It can be found here.
When a child learns to count there are various stages that they go through:
string level
unbreakable list
breakable chain
numerable chain
bideirectional chain
Only when they have mastered all of these are they really competent at counting.
Using a ty/teen number square (below) is a really useful tool when a child has a problem with ty and teen numbers.
An subitizing and using ten frames is another really useful method to support them.