A good place to start is a dictionary.
There are plenty of good and free ones online, and I will go with Lewis & Short.
The entries for these two words offer the following among the possible translations:
etiam:
annexes a fact or thought to that which has already been said, 'and also', 'and furthermore', 'also', 'likewise', 'besides', 'one thing more', 'so', 'conversely', 'and even', 'yes indeed', 'even yet'.
enim:
a demonstrative corroborative particle.
'truly', 'certainly', 'to be sure', 'indeed', 'in fact', 'certainly', 'for'.
Follow the links to see the actual dictionary entries and further details.
It is very useful to learn to navigate such entries.
My lists are not exhaustive, nor is a list of English translations a perfect description of a Latin word.
The different contexts and nuances are explained for words like these in great detail.
My goal with a short list of translations here is just to give a quick idea — but I wouldn't go down to just one translation, as that tends to be misleading for words like these.
As a quick summary, etiam adds something (and can sometimes play the role of et) whereas enim is about strengthening.
The two do overlap somewhat, but typically etiam is not about strengthening and enim is not about adding.