1) Stand tall! He should dance at his full height; it looks better than crouching, and gives you a solid frame to work with. You should also dance at your full height, and straight rather than bending your head back to look up (maybe once in a while, but for the most part your head should be even). On the other hand, you should /not/ tiptoe or stretch up; since it’s harder to balance if you aren’t grounded.

2) Focus your energy! Even though ye’re standing at different heights, your connection should focus on the space between. He should focus on the connection through somewhere between his lower ribs, or his bellybutton, and you should focus the connection through somewhere between your sternum up to your collarbone. This doesn’t necessarily mean you’re physically connecting at these points, but you are working to keep them in relation to one another.

A much shorter way of saying the above: Be who you are, and meet where you meet.

I’ll also agree with a previous answer about beginner’s classes; Tango is a social dance, so you get to dance with everyone, and classes often get people to switch partners
References :
Personal experience