Hi William,

Normally adverbs which modify verbs (and adjectives) will follow (or precede) them in the sentence.

In the case of adverbs which end in 'ment' , they will almost always follow the verb they refer to, with the exceptions of 'heureusement' or 'malheureusement' which can be used at the beginning of a sentence or on their own as an exclamation.

Malheureusement, il allait trop vite = Unfortunately, he was driving too fast

There are some link adverbs (ainsi, à peine, aussi, du moins, peut-être, sans doute) which  can head a sentence and sometimes they will be followed by an inversion of subject and verb. e.g. 

Ainsi nous a-t-il surpris! 

Peut-être va-t-il revenir...

Placing the adverb in the wrong place in French will sound like 'yoda speak' of 'Star Wars' fame and it is very instinctive...

Hope this helps!