Need payment button for my website

Paypal offers both

there is a pay now button and set up if you think no one will purchase more than one thing

there is also a shopping cart set up for paypal which will accumulate the buy this clicks, add sales tax when applicable and take payments.

The advantage of paypal or a similar site, IMO, is that the transaction does not hit your site so there is no requirements for credit card security, paypal handles all that.  Just leave the actual transaction receipt in the paypal account and only get an email from them telling you what was ordered, by who, and where to ship it if you are selling physical goods.

My recommendation is to never use the buy now button, always use the shopping cart set up, you never know when a customer will want more than one thing, or if you will offer more than one thing.

Hi @ScribeMarjie. Congratulations on starting your new business! I use both Square (SquareUp.com) and PayPal - they both have similar fees for accepting payments. It may be worth exploring passing that cost onto your customers/clients.

PayPal has 3 options - and they're all useful depending on what you need:

1. Subscription: for clients who'll need monthly services (e.g. Here. scroll down, click a "Buy Now" button). I choose to use the individual "buy now" buttons for this, because it's the only way to create a URL (instead of just a button code) on PayPal. This allows your customers to pay via PayPal or Credit Card! I can also easily use my websites own button designs, instead of PayPal's buttons. 
2. Shopping Cart: for clients purchasing multiple writing services (e.g. Here. scroll to bottom of page, click "Add to Cart"). Once you create the button, it creates a code that allows you to post that button on your website and, as @Rustler mentioned, allows customers to return to the 'shop' to add more. 
3. Buy Now: @Rustler 's favourite (I get it) may still come in handy for something. I don't have my PayPal account open right now, but really take the time to think through your clients/customers' behaviour, before you decide which buttons will work in each situation. 

Hope this helps!