The Blades have collected 11 points from seven games since Clough took charge and the former Derby boss is keen to maintain his side's momentum as they bid to climb the table.
But any possible signing will have to match the former Derby boss' high standards before he will consider adding them to his squad.
"The biggest thing for me is always a player's character," Clough told the club's official website.
"That's something I like to find out a lot about, a major factor when we are looking to sign a player.
"We always endeavour to watch every single player we want to sign and if all of us, as a staff, give them a tick, then the answer is usually a 'yes'.
"January is a funny transfer window. I find you get better value for money in the summer, but we will see what happens."