Watch your replays. Honestly, that's step one. Also you have to be willing to look for your faults before you blame game balance and bad RNG for your losses. If you do both of those things, while watching streams every now and then to see how good players manage their armies, you'll improve in no time. Also, consistently playing people better than you will help you improve much, much faster than stomping randoms on the ladder. Find a partner who is a better player than you, and square off against him.
+7
-Unit preservation
-Reading the flow of the game. How much resources both you and your opponent have. What did he spend his muni/mp early on? What about fuel?
-Build your own flowchart of actions: while this isn´t SC2 where you need to mechanically do repeating things, it helps to have in mind a certain routine.
-SLOWLY start improving your micro: start to slowly add hotkeys and control groups into your play.
-I like to compare some situations with Poker. You need to know when is it worth it to take calculated risks and if it´s worthy or not. This mostly comes with experience.
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-I guess this isn´t directly answering your question on "how to slow down the game". If you do this flawlessly constantly, you slowly start getting used to it without requiring so much effort. This put you on the "zone" where you mechanically do things without even thinking of it.
Putting a mine which 30s later helps you destroy a tank, repositioning an MG prior to see the flank coming, putting some units for an ambush, etc.
-Avoid distractions such as discussing with other people ingame, music (while i like to play with it, it makes me miss audio cues), look at how fancy a unit is attacking or moving
, etc.
-Take breaks. After a long game or during a session, take a couple of minutes to move, drink/eat, do something else. Fatigue is something that affects us all, newbies and pros.