The beer thing may work, it may also stop you cumming.

Definitly change the sex - eg let her ride you, both sitting up. Or take her from behind, and grip her ankles. or go down on her, gently smooth her pussy and clit, while very gently opening her labia wider, run your tongue gently around her anus, not in (can if you like) and tickle her ring with your finger.

ETC

Mainly enjoy it!!!

Andrew