I installed a new bathroom sink+faucet, it leaks when draining water. Here are my questions:

1. I put a thin rubber gasket under the flange, didn't use plumbers putty.
2. Under the sink, I put a large washer next to the sink opening, then a fat
Tapered rubber gasket , then tighten with a large nut - wrong sequence?
3. Didn' use teflon tape screwing the pop-up to the flange body.
4. The pop-up stem doesn't meet the j-pipe opening, so I used an accordion
Type plactic pipe to match the j-pipe opening to the pop-up pipe. Is there
A better way to match the two.

Water seems to leak around the pop-up assemply and/or the accordion
Type pipe I used. Need help.

The Glacier Bay faucet install instructions were terrible.

1. I put a thin rubber gasket under the flange, didn't use plumbers putty.
Ahh! Your first leak. You should have used plumbers putty or silicone jel to form a seal.
2. Under the sink, I put a large washer next to the sink opening, then a fat
Tapered rubber gasket , then tighten with a large nut - wrong sequence?
Boy! You're batting a thousand on this installation. The tapered washer goes next to the sink followed by the fiber anti-friction washer followed by the nut. Your second leak.
3. Didn' use teflon tape screwing the pop-up to the flange body.
You don't have to teflon those threads.
4. The pop-up stem doesn't meet the j-pipe opening, so I used an accordion
Type plactic pipe to match the j-pipe opening to the pop-up pipe. Is there
A better way to match the two.
The best way would be to reposition the trap, however if the offset isn't too great the accordion pipe should work if you get the connections tight.
Go back and redo the job. Let me know how you make out. Tom