Things I try to do:
--focus on what the instructor is trying to show you; force yourself outside of your typical training "rut".
--don't try to correct your partner unless they are going to hurt you or unless they ask you too. i.e. don't "teach" your practice partner.
--Don't assume that hakama/blackbelt=super duper ukemi person and that no hakama/whitebelt=clueless beginner. Hakama or no hakama-wearing and black belt or white belts are all worthy training partners.
--along with the above, start at a slow pace and build up. If someone goes too hard on you, say so. If you want more, say so.
--smile and say, "hello, where do you train?"