Use the smaller sized office clamps to hold it in place. These can be placed on a few sides. Check that they do not collide with your printhead.

Then, prep it with a light ScotchBrite scrub. Just enough to see the light abrasive marks and a bit of texture in the surface. Finish with high purity isopropyl and a dry cloth buff. If you want, you can do prep away from the machine. I do because I disturb the level less. You can use a fresh, green type found in the grocery store for cleaning dishes, and or the more industrial purple. Just need to scuff the surface a tiny bit.

That gets rid of dust, oils and such. And the light abrasive gives the polymer a better mechanical bond.

Set your bed height to about one half of your nozzle diameter.

0.4 nozzle = 0.2mm bed to nozzle tip distance. Ordinary weight printer paper is about this amount.

Level your bed using the paper at all four extents. You should feel just a bit of drag resistance between nozzle and paper.

For most PLA, heat the bed to 65, maybe 70C and set your first layer height to half your nozzle diameter. 0.2mm again.

I like to print a skirt around the part to let flow settle before the first layer is made.

No glue stick, hairspray or anything needed.

Gatolite grips many other polymers when warm, releases nicely when cool.

I prefer G10 type.

For glass, do all the same things, skip the scotchbrite and add pvb gluesick in an even coating in the region your part will be. Let it sit a bit with bed at temp, then kick off your print.

Regarding wet filament, it can cause some problems. If you doubt your filament, you can quick dry some. Unspool a few meters, turn your bed heater on, set to 50C and lay it on there. Cover with light foil, put a small hole in the middle, wait an hour, then try printing with it. You want the foil just sitting over the filament, but not tight. Some light airflow is good to carry moisture away. It will come in through the sides and out the hole.

Use exact same settings to troubleshoot this moisture idea. If it sticks, dry your filament. If no change, your problem is not moisture.

That same idea applies to everything. You need to isolate problems to materials, settings, machine, environment, etc...

All this assumes some open bed type home machine, like a Prusa, or Creality type.

Once you do get adhesion, archive that gcode and process. When you have trouble again, pull that filament out, repeat exact process again to baseline your setup.

Always baseline when introducing a new idea.

I like to use some little cubes, say 9 of them, spread across the build surface. Run that job, make sure it sticks, then run parts. A good baseline takes roughly an hour, maybe a bit less once you have done it a few times.