Alan H: Fortunately, I already have a PayPal account which will be my primary payment method.
PayPal may serve you well as a merchant or when you are transacting from some parts of the world, but from my own experience, as a freelancer from Kenya, it'd be my last resort. It's still holding my money - almost $500 - since time immemorial (almost a year!). Wasn't earnings from Upwork, though.
Since MPESA has become part of our lives as long as you are resident in Kenya, and you need not do a thing to have it work for you at Upwork, I'd advise you make it your default money transfer method. Alternatively, include it as a choice in the payment options section.
For one, with MPESA, charges are fixed irrespective of the amount involved - $0.99 (as opposed to PayPal that deals with percentages). And if you are thinking of security, MPESA is secure. Equity has a good service as well, and it was my best option before MPESA came into the picture, but MPESA beats it in speed. The bank promises payment within 3days, though I must say my money reaches me in just a couple of hours. If I make my withdrawal, say, 3am (which I sometimes do), my money is in the bank within the first hour of banks opening - meaning 9am. And even for those who receive theirs in 3days, it isn't such a long waiting period.
When MPESA came to Upwork, they promised to make funds available within 2hrs or so of your withdrawal, but that seemed to have lasted a week or two, and things became even better. It takes me about 10min after withdrawal to hear the 'ping' that alerts me my money is in my MPESA account and available for use. Let's say, when you use MPESA on Upwork, it's as if you are transacting from within the country, either from a retail agent or from a local bank. Long live MPESA!
Oh, yes - about the rates.
Timothy M: The transfer rate from US dollars to Kenyan shillings as used by Upwork is however questionable.
Upwork is taking care of us by monitoring the rates the agents give us. So, one of these days you may see some amount sent into your MPESA account to make up for past transactions done at lower rates than you deserved. Of course discrepancies for individual transactions may be minimal in absolute figures, so Upwork does a review for a certain period and not on a day-to-day basis. I've been a beneficiary.