I am a straight male. Recently I have become obsessed with sucking on my dildos that I have. I have gotten better at oral sex on cocks but need some advice. I can go all the way down on my 5 1/2 inch dildo, am working on my 7 1/2 incher, but really want to go all the way down on my 8 incher that is about twice as thick. What are some tips on how to deepthroat?