I am trying to get approved for merchants so i can take payments on my website

Hello, i am trying to start taking payments for my company.
I know the initial registration is for me to do but i need help with getting the website and everything else ready so that i will get approved and be able to start taking payments.

i have tried in the past and been denied

i want to work with things such as
paypal
sumup
squareup

Whichever would be best advised and if somebody has experience that would be great.