Using a donation model on a blog needs to be done judiciously. If your site is very commercial in nature, asking for donations can seem presumptuous and even greedy. If you walked into Walmart and the greeter had a collection jar, it would be startling, to say the least.
That said, the donation model works very well in some instances. If you run a charity, non-profit, or site that focuses on a cause, it may be very beneficial.
Your site doesn’t even have to be an official site for a charitable organization. If you are collecting funds for a cause that your readers care about, this is an option to consider. For example, if you run a blog focusing on pets, you might raise money for a pet adoption shelter or the Humane society.
Receiving donations on your site is as simple as adding a little PayPal code that embeds a donation button that is connected to a PayPal account. Here is a working example: