I came up with a interesting method and that is to just assume it won't work.
Tell yourself "I'm gonna burn it." or "I'm not going to hold it in long enough", something like that.
Just today I had this batch of aya which I wasn't sure if I fucked up or not, I just drank it like some hard liqueur. On a evening, before bed, expecting nothing to happen.
Then all of the sudden, BOOOM! I couldn't even read laters. I think to myself, what the heck, I don't even feel tripped out, how the hell am I having such hardcore visuals?
I totally forgot about it, and went on with whatever I was doing at that moment.
I didn't stress out "Well shit, I'm not going to be able to sleep if it works" or "What if I have a bad trip, my mind is all over the place lately".
Needless to say, it was a very positive trip that came out of just expecting nothing to happen.
Try that.
If you think it won't work, you won't anticipate anything, when you don't anticipate you don't feel anxious about anything, when you're not anxious well what are you afraid of then? The boogieman?
Don't stress about letting go, if you just puff and not think about what's going to happen next at one point you're going to puff enough so that breaking through is no longer a choice.
And once you get there, well, it can't get any worse than what's happening right now to you. Why panic if it can't get any more intense than that? I mean you're in it at the time, and you're fine and you will be fine, what could possibly happen that it takes a turn for the worse than it already is?
I hope you can make sense out of my improvised monologue. Still tripping a little.
Anyways, bottom line, there's no reason to be afraid. You've been there, and you made it, what makes you think it's going to be different this time?