From a male perspective, ...
Get to know the other person well before going where ever they are with plans to marry (I knew my own wife very well through several hours of chat every day for about a year).
Know about their friends and family. If they're interested in you for the right reasons they wont be able to wait for you to get there so they can take you around to meet everyone.
On the other hand if they don't want to introduce you around I'd find that very fishy and wonder why they don't want you to know the people that mean a lot to them.
In some cases I'd find it concerning if I'm 61 and a 25 year old hot little thing is putting the moves on me. What 25 year old wants to get intimate with someone who's old enough to be her dad, ... especially on a long term basis?
So many old guys get sucked in by that. In some cases it might be a genuine attraction, .. but in 999 out of 1,000, .. I think not
If you want extra closeness make sure the partners spiritual beliefs are close to your own, .. or at least that you can live with what the other believes without expecting them to change for you. If it does happen it sure wont be over night . ;D