I used to basically curl my bottom lip inwards and blow hard to go higher. Airstream went down and all the pressure went on the top lip. I worked hard on thinking about the airstream up as well as constantly blowing into my hand using the mouthpiece visualiser (no buzz) to make sure my airstream was straight or heading up. Thinking about the feeling. Learning not to ‘kick’ the air. Then I had to try and forget this whilst I am on a gig.
Hope that helps!