To introduce a contrasting point:
* However,
* Nevertheless,
* On the other hand,
* But,
* Despite that,
* In spite of that,
* That said,
* Having said that,
To summarize or conclude:
* Therefore,
* In conclusion,
* To sum up,
* In short,
* So,
* Ultimately,
To transition to a new point:
* Moving on,
* Now,
* Furthermore,
* Additionally,
To emphasize a point:
* It's important to note that,
* Keep in mind that,
* It's worth considering that,
The best alternative will depend on the specific context and what you are trying to convey.