1st and even 2nd layer not sticking

Hi,

I'm new here, so hello to everyone :)

I have a creality CR10 printer. I've been struggling with it for more than a year now. This is my first 3D printer, and had never played with a 3D printer before.

I always had troubles with first layer. I would say only around 10% of my prints were successful, so I was a "bit" frustrated... I always do a bed levelling before a print. The technique I use is put everything at print temperature, and then use a sheet of paper between nozzle and bed to make the level at different points.
But I always have troubles with this 1st layer not sticking. And sometimes, even if 1st layer seems ok, the 2nd layer might not stick to first layer (that is even more frustrating...).

Searching in forums, I found many things I tried to improve it :
- tried different brands of filaments (but always PLA filament)
- replaced bed glass with mirrors
- tried UHU stick glue
- tried to tape the bed
- tried hairspray
- tried a higher bed temperature (usually set to 60?C)
- tried skirts, brims

I never found a good setup.

In attachments, 3 pictures of a 2nd layer which fails.

If you have any suggestions, I would love to try it.

Thanks !