He stated that it will take a few months before any real assessments can be made of his team and their likely objectives for the campaign.
Villarreal were surprisingly relegated from the top flight in 2012 but needed only one season to get out of the Segunda Division as they finished runners-up to Elche last term.
The Yellow Submarine finished that campaign with five consecutive victories and followed it up with a promising pre-season, including claiming notable victories over Fiorentina and Sporting Lisbon in their final two friendlies.
That has led to a feeling of optimism around the club heading into Monday's trip to fellow promoted outfit Almeria, but Marcelino is refusing to get carried away.
He said: "It's been a long pre-season and without doubt we're keen to start the season. The team has high hopes and we notice that the fans are also full of hope.
"It seems like there are lots of good vibes around and an expectation that Villarreal can do good things, but on that I'm also quite cautious.
"In football when you lose 4-0 it seems you're already relegated, while when we beat Fiorentina and Sporting Lisbon with room to spare it seems that we are going to conquer the world.
"You need to wait 10 or 12 competitive games and we will have a more realistic idea of what we can do this season."
Villarreal took four points off Almeria last term but were beaten 1-0 by the same opponents in the close season, going down to a second-half penalty.
Almeria, who were promoted through the play-offs, will be hoping to repeat that success but new coach Francisco Rodriguez - at 35-years-old the youngest manager in La Liga - knows it will be far from easy against a Villarreal side he has huge respect for.
"That match will have no bearing on this game in the official competition," he said.
"We're going to face a great opponent who can count on international players, who have a very high level in their squad and a good coach. Their potential is very big."
He added: "We are working hard to try and be at 100 per cent in the game with the objective of winning it and getting the three points."