There are many options available for accepting payments (Paypal, Authorize.Net, personal/business check, escrow, etc.).
Is there a good way to decide which option (or combination of options) should be used to reflect professionalism as well as protect the freelancer and client?
Payment options are really less about the freelancer's professional, and more about the kind of customers the freelancer works with and what they are comfortable with.
For the customers that I work with (small, local businesses), I am paid via business check. I'd prefer to use an electronic payment, but my customers are comfortable with the current approach and in 10 years of freelancing I've never had an issue.
Other customer types may need different options. But I don't think it reflects on the freelancer's professionalism, unless they will only accept payment options that repeatedly aren't appropriate for the type of customers they are working with.
For a freelancer starting out, any method is usually fine. When I was freelancing, I accepted Cash and Cheque, simply because I was not big enough in my first year to take a Credit Card while still making a profit. Company cheques are usually safe, but there will probably be a couple in your lifetime that bounce. The main thing is, you want a paper trail.
This can be accomplished even with cash, by issuing a receipt of course, but Credit Card processing, Cheques, PayPal, etc. will all have receipts and paper trails to go back on as well. In Canada, banks charge the least amount for depositing company cheques to small business/freelance workers; the rates for Visa can be between 6-9%, plus any extra bank or machine fees! This can easily turn out to be a lot of your profit, and should be taken into account. One trick to avoid some of these fees is to offer a discount if paying by cheque or cash, but do not increase the price for Visa or Mastercard; that is illegal in Canada.
In theory, it will depend though, again on the project size, and your fees for accepting payment. I do not have experience receiving money with Paypal though, so I would be unable to comment on that.
This is very much personal preference than reflecting professionalism. Not sure if I can plug a specific service, but I switched to Harvest about a year ago and haven't looked back. I can now accept all major CC's (via Stripe) + paypal and a few other options if I wished to activate them.
Obviously clients can also mail a check. 9/10 clients pay via CC. Occasionally I have a client that wishes to do bank transfer or something odd, but it's pretty rare.
The professionalism means you should offer the payment options that would be the most comfortable and available to [al]most [all] your customers. It's very annoying when someone offers only those payment options who are not available to you.
You should for sure accept bank payments, since it will be the options available for the most of the customers (in most European countries the bank account is mandatory for every company, so you can expect that every company-customer would be able to send you money via bank payments). Checks and cash when applicable.
Paypal and other similar services are great for international payments, but it is (in my opinion at least) very unprofessional to accept only such payment methods (since the customers that have no credit cart/paypal/similar would be opted out).
If you have a lot of customers in EU, it would be very recommended to open a bank account in EU, the same applies to other regions.
