I don't usuallytend not to make decisions from the heart.

Your way was correct, however this way is even more natural!

I don't think it would be a good idea, expecially if the themedecision is important.

Theme isn’t used in this way: theme = overarching idea. Using decision as it is is the only correct way in this context

For silly things, canmatters, it would be ok.

Would must still be used as you are talking about a hypothetical situation. Matters = complications/predicaments. It is better suited here instead of things; which is ambiguous. However things is still correct ambiguous also makes your writing more sophisticated

IfWhen I go to the cinema and I don't know the movies neitheor the actors nor actresses, then, doesn't very import if, then, it’s not important whether I watch one or the other.

You are talking about a past occurrence: use “when”. Do not use if; if implies a hypothetical situation like: if I do x, y will happen. Cause and effect.

In the wWorset case scenario, I will have lost two hours.

Hypothetical scenario: outcome < is the formula. “Worst case scenario” is a, sophisticated phrase to structure this type of sentence.

Important decisions should be ¶
makde with/(on the basis of) common sense.

“Should be + verb” this is a complex structure to explain and justify, however, in this context we would always say “made”.

Only when the information is not enough, we can need of theWith insufficient information, we must make use of intuition.

Your sentence is technically correct, however we would never phrase it in this way in a natural sense.

I don't think it would be a good idea, exspecially if the theme isit is significant or important.

For silly things, it can be ok.

If I go to cinema and I don't know the movies neither, the actors nor actresses, then, doeit isn'’t very import if I watch one or other.

In the worset case, I willould have lost two hours.

Important decisions should be makde withusing common sense.

OIt is only when the information is not enough, we can need of the that we rely on intuition.

I don't think it beis a good idea, exspecially if the theme isit is an important topic.

For silly things, it can be ok.

If I go to cinema and I don't know neither the movies neitheor the actors norand actresses, then, doe it isn't very important if I watch one or the other.

In the worset case I will have lost two hours.

Only when the information is not enough, we can need of theuse our intuition.