To indicate more information:
Besides
Furthermore
In addition
Indeed
In fact
Moreover
Second...Third..., etc.

To indicate an example:
For example
For instance
In particular
Particularly
Specifically
To demonstrate
To illustrate

To indicate a cause or reason:
As
Because
Because of
Due to
For
For the reason that
Since

To indicate a result or an effect:
Accordingly
Finally
Consequently
Hence
So
Therefore
Thus

To indicate a purpose or reason why:
For fear that
In the hope that
In order to
So
So that
With this in mind

To compare or contrast:
Although
However
In comparison
In contrast
Likewise
Nevertheless
On the other hand
Similarly
Whereas
Yet

To indicate a particular time frame or a shift from one time period to another:

After
Before
Currently
During
Eventually
Finally
First, . . . Second, . . ., etc.
Formerly
Immediately

Initially
Lastly
Later
Meanwhile
Next
Previously
Simultaneously
Soon
Subsequently

To summarize:
Briefly
In brief
Overall
Summing up
To put it briefly
To sum up
To summarize

To conclude:
Given these facts
Hence
In conclusion
So
Therefore
Thus
To conclude