Pretty broad question, there. The ideal first microscope for me was a pretty bad toy given to me by Santa in 1970 when I was 10 years old, because it ignited a lifelong love affair with microscopy even if it was largely useless. That may not help you, so try this: for many folks coming into the hobby as adults, an inexpensive brand new Amscope or equivalent is the path to bliss, but for others, a much higher quality but older used instrument is true enlightenment. Not that inexpensive new scopes don't offer quality -- that's actually a bit of a debate I don't get into because both sides are right as far as I'm concerned, because I believe it to be a matter of "different strokes for different folks."
So, in my opinion the first question to answer is do you think along the lines of cheapest brand new scope with support, warranty, etc., or maximize bang for the buck going the used equipment route?
The next question is, as in any hobby ... budget?
Next question most ask is what you want to look at, but I'm not so sure about that one. I expect most newcomers really don't quite know, and want to explore all possibilities. For this a "biological microscope" will do, but it's a pretty vague term. The good news is 90% of microscopes as we know them are "biological" ones, so no need to sweat it.