Looking on the internet deeply has found these results:

I must be careful not to lose is the most popular phrase on the web.

I must be careful to not lose 11 results on the web	I must be careful not to lose 1280,000 results on the web More popular!
Some examples and use cases from the internet:	Some examples and use cases from the internet:
Be careful, you could lose your fingerprints. We have to be careful not to lose the emotion. Be careful not to lose your 10000 francs... Earlier, I heard one speaker say that we must be careful not to lose our citizens. I have to be careful not to lose my footing. Be careful, don't lose my tapes. Be careful not to lose your soul. Be careful not to lose his job.	Be careful not to lose his job. Be careful not to lose your 10000 francs... From now on, we must all be careful not to lose the King's love, or everything is lost. I have to be careful not to lose my footing. Earlier, I heard one speaker say that we must be careful not to lose our citizens. You just got to be careful not to lose your separate selves along the way. Be careful not to lose your soul. We have to be careful not to lose the emotion.

I must be careful to not lose

11 results on the web

I must be careful not to lose

1280,000 results on the web

More popular!

Be careful, you could lose your fingerprints.
We have to be careful not to lose the emotion.
Be careful not to lose your 10000 francs...
Earlier, I heard one speaker say that we must be careful not to lose our citizens.
I have to be careful not to lose my footing.
Be careful, don't lose my tapes.
Be careful not to lose your soul.
Be careful not to lose his job.

Be careful not to lose his job.
Be careful not to lose your 10000 francs...
From now on, we must all be careful not to lose the King's love, or everything is lost.
I have to be careful not to lose my footing.
Earlier, I heard one speaker say that we must be careful not to lose our citizens.
You just got to be careful not to lose your separate selves along the way.
Be careful not to lose your soul.
We have to be careful not to lose the emotion.