Heres a guide
Start a new run, Don't Buy any flavored cookies. they will ad to your clicks per second
Play as you usually would and keep grinding to the top until you get to 999B cookies in bank.
Sell everything. selling doesn't ad to cookies for some reason just keep clicking to get to the exact number.
your cps should be 1 after selling everything, that should also take your clicks to 1 (Note may take a while).
Keep large numbers on so you can track you total cookies far better. Once at exactly 1,000,000,000,000 cookies, ascend and get the achievement.
Edit: One more thing: be carful of golden cookies near the end!