The Champions League outfit made a slow start to their La Liga campaign, but have picked up six points from their last two matches.
"The most important thing is the match tomorrow. We have secured two consecutive wins, we want a third one," Arrasate told reporters at a press conference.
"We understand that this is very tough in this league, but we also know that if we win tomorrow then we will take a further step forward and we are just thinking about that.
"Opponents Valladolid? They are tough. Few teams play well at their ground. We will have to get it right, be better than the other day, and closer to the best version of Real Sociedad so as to win.
"We have to make things right, Valladolid will tighten things up, but we have to be protagonists, try to get the ball, open up the field and look for a spark in attack, do what we know. If the opponent counters, then it can cause us problems, so we will have to look out for that and it will be difficult."
Sociedad currently sit ninth in the La Liga table.