I think you are getting a cross section of replies because there isnt one standard answer.
I've been amazed at how many bottom guys need no preparation at all, so...
But, for me,
a lot of foreplay...
a lot of fingering,
and a lot of lube........
And for me it is easier to straddle the guy and
be on top...it is much easier to get used to
if you are in control of where things are going.
Breathe...
have patience...
just because it burns a little(or a lot) at first, dont be discouraged...
hop off for a second.
The next time you hop on it should go in easily.
And the most important thing is to be really turned on.
It is the key, for me, for an easy entry.
um...
ENJOY!