URL Obsession

If your prospective agent passes this initial scrutiny, your next step is to look out for up front requests for fees.
Aside from minor costs for certain mailings, copies and the like, which are accrued until you receive your advance, there should be no reading or editing fees, sometimes disguised by unscrupulous and incompetent agents as so-called marketing or submission fees.
If your potential literary agent can provide you with verifiable sales and does not want upfront or down the road money, it’s likely they’re legitimate. This type of literary agent has the contacts and competency to be your successful advocate to legitimate publishers. They know who’s buying what and when.