I once wrote an article about my experiences with bridge novices. They often dwell in, what I then called, the 'magical universe'. The article has lost none of its topicality.
My students eye me in astonishment when I tell them I never count trumps - which is the truth.
Active counting is unnecessary. An example: if in a 4-4 trump fit declarer draws trumps twice, all he has to do is register whether both opponents follow suit. If so, only one trump remains to be drawn. After all, the suit is divided 3-2. That is why I do not count, nor think along the following lines: 'I have played the suit twice, all followed suit, meaning eight trumps have been played; I have four left, this adds up to twelve, so there is one left to draw.'
There are essential differences between these two methods. First: 'thinking in patterns' (as I call it) hardly consumes any 'thinking energy', since the brain is in automatic mode. Secondly in thinking this way students gain a clear insight in the bridge game in a natural way. They succeed more easily in overviewing the possible distributions of the missing cards.
Because that is what bridge is all about: declarer tries to find out what cards his left opponent holds and thus what cards his right hand opponent holds. In defence that amounts to: 'Which cards does partner hold' and 'which ones does declarer hold'. Of course this is not limited to distribution; also the high card points and therefore the honour cards are of great importance.
Training the way of thinking described above is easy. Make sure you know by heart the different ways thirteen cards can be distributed. When picking up a hand, sort the cards per suit, have a look at the distribution and then put the cards face down on the table in front of you. Then silently repeat this distribution to yourself: 'A 5-4-3-1 distribution' or: 'A 4-4-4-1', 'A 6-3-2-2' and so on. This may sound a bit childish but it works. Very soon you will be totally familiar with the numbers.
Being declarer, construct a picture in your mind of the ways the suits can be divided between the opponents. This will probably not always be relevant to your line of play, but force yourself to do it every time and for all four suits.
You can also train this when you are defending. How are the suits distributed? What does partner hold? What does declarer hold? Make presumptions: 'If partner has two hearts, declarer has five.' Is that possible? Would declarer have bid differently holding five hearts?
Once a student defended her returning a heart (partner had lead that suit) in saying: 'Maybe partner can ruff now.' Dummy had a doubleton in hearts, she had three herself. When I suggested that in that case declarer might have bid his seven card suit, she first eyed me speechlessly and then burst out in laughter. She thought herself very stupid. Again this was not a matter of stupidity but of not thinking in the right direction. She had not arrived yet in the magical universe...