“One key to avoid this kind ..” is not correct.
Definition and pronunciation of key | Oxford Advanced Learners Dictionary
a thing that makes you able to understand or achieve something
key (to something)
The key to success is preparation.
key (to doing something)
The driver of the car probably holds the key to solving the crime.
“ …start think…” is not correct.
Wrong: start do something
Correct: start to do something
Correct: start doing something
Definition and pronunciation of start | Oxford Advanced Learners Dictionary
start to do something
It started to rain.
Mistakes were starting to creep in.
start doing something
She started laughing.
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