The Navarrans have scored just 23 goals this season, fewer than any other team in La Liga, and the forward believes they need to exploit their ability in the air, especially from set pieces.
He also called on all the outfield players to contribute more to the team's attack.
He told reporters: "We know that we are creating few chances, and there's nothing else for us to do than focus more on it, and attack more in numbers. We need to have more players going forward. Giving the forwards support could be the key to us scoring more goals."
He added: "Our centre-backs have been having shots but haven't been hitting the target. I have been telling them to keep trying. We need to improve our heading because we have a lot of power from dead ball situations."
Sola also dismissed talks that the team were in a worrying situation after losing three games on the bounce.
"We have lost three games but there is no problem, I think the team are fine," he said.
"We are a better team now than we were at the start of the season. Even though we have lost three games in a row, the team are still united.
"The players are less rigid and are playing with more bravery, for example, in making that final pass. We aren't in an emergency situation, the dressing room is relaxed."
Sola is expected to return to the starting line up against Valladolid after missing the 2-0 defeat to Atletico Madrid because of injury, while defender Ruben Gonzalez is also fit after recovering from an ankle sprain.
Valladolid coach Miroslav Djukic has acknowledged that his side are in for a physical match against the Navarrans.
He told reporters: "We know what [Jose Luis, Osasuna coach] Mendilibar's teams are like, they are always hard working and full of fight, we'll have to be prepared for them. They have hard working players, play with a lot of intensity, vary the play and put a lot of crosses into the box."
The Serbian coach did not confirm whether Patrick Ebert would make his first start since injuring his thigh 10 weeks ago, but indicated he would play some part in the game.
"We'll see how he is because he's been training at the maximum for two weeks and I wouldn't discount him starting," he said.
"We will keep checking on him, we would like him to be fully fit if he does play, although from what I have seen he isn't any slower, he's not the type of player that does things in half measures."
Dani Larsson and Victor Perez, however, have not recovered from their injuries in time and will play no part in the match.