I didn't bleed at all when I lost my virginty, but I had been doing horse riding for years and have a sneakling suspicion that my hymen was broken already. White sheets might be a bad idea, but a towel shouldn't be necessary. It might only serve to make her more nervous.
It might hurt her, so you need to make sure she is soaking wet first. Have some lube handy. When you come to enter her, be slow but firm, and stop if she asks you to. Make sure there is lots of kissing and cuddling first, so she is relaxed.
Communication is the key.