H and K
KY gel, which is available from most supermarkets is as good as the original gel supplied with the pump. Trimming the pubic hair will help to get a good seal between the pump and body and a small amount on the tip of the penis will help the penis slide up the tube. Getting the pump started and sealed can sometimes be easier if you are in the standing position. Just be aware that we are all different and you could get a reaction to different products.
Good that you had a demo, my first time using the pump and rings I managed to get a testicle inside the ring. Ouch. Some guys find using two larger rings keep an erection better than one small ring.
Added. Have a look at this post for some useful info especially from one of our ladies. http://community.prostatecanceruk.org/posts/t11301-The-ED-Pump