Plastic solder sucker is ok if the tip is silicone. But yeah, quality solder makes a difference.

Do you have a little pad with brass or steel wool on it, to clean the tip of your soldering iron? I find that makes a huge difference, the solder won’t stick or flow properly if the tip gets oxidized on the surface.

I have gotten in the habit of jamming the tip into the brass wool 3-4 times every time I pick up the soldering iron and it keeps it fresh and consistent every time.

Something like this: Soldering Tip Cleaner Soldering Iron Tip Cleaner Brass Tip Cleaner Kit and 6PCS Brass Ball Wire-type with 1PC Ball Shell Holder for Cleaning Solder Irons and Tips https://www.amazon.com/dp/B07FX4V7PZ/ref=cm_sw_r_cp_api_glt_i_1N39A8DDA63J8CEEW2WA