A victory would complete a superb first month of the season for the Ospreys with wins over Treviso, Edinburgh and Connacht and a more than credible draw with Leinster in Dublin already in the bag.
"We are really pleased to be where we are in the table four weeks in and after three games on the road," said Tandy.
"But we aren't going to allow ourselves to get carried away. There's plenty of room for improvement in a few areas of our game and we are going into a tough run of fixtures where we are going to have to move up several gears to keep building momentum.
"Ulster on Friday night is as difficult as it gets. They've got a strong squad with world class players. And as they've shown over the last two seasons in getting to Heineken and PRO12 finals, they can beat anyone so we are going to have to be at our very best."
For tomorrow night's game, Tyler Ardron makes his first Ospreys start in what is a formidable looking pack. Welsh internationals Ryan Bevington, Richard Hibbard and Adam Jones pack down in the front row with Canadian Ardron supported by British Lion Justin Tipuric and Joe Bearman.
"It should be a cracking contest and is the first of two home games on the bounce against quality opposition," said Tandy.
"This is what we've been building towards in the opening weeks of the season and it's a period that any rugby fan will be excited about.
"Our fans will have a massive part to play over these two games, helping to create the kind of atmosphere the team can thrive on. The players really appreciate the support they get each week, and hopefully with two massive games coming up, the performance off the field will go up several levels as well as on it."
For Ulster, Irish wing Andrew Trimble returns after undergoing surgery on his finger three weeks ago. He starts on the right wing in place of former Osprey Tommy Bowe, who has failed to recover from a dead leg sustained in the bonus point win over Treviso last Friday.