United lost 2-1 at Hearts on Sunday after Brian McLean and Gavin Gunning contrived to fail to clear allowing Ryan Stevenson to score before the Hearts midfielder netted a penalty.
The visitors replied through Keith Watson, but were unable to breach the Hearts defence again as they fell beneath the Edinburgh side in the Clydesdale Bank Premier League table.
That result came a week after seeing a three-goal lead slip against Inverness and a point rescued with a stoppage-time penalty and Houston has called for United to tighten up and add to their two home wins this term in Wednesday's Tayside derby.
"St Johnstone's a tough match, but we have to start putting a run together with regards to our home form," Houston said. "Our away form has been good. We played well (at Hearts) and lost the match, but we have to make sure we start a wee run at home.
"We have to clear our heads of our result and try to get a result against St Johnstone on Wednesday.
"We have to really, really stop giving soft goals away. We have to make sure we cut out the errors that we're making.
"We can play as good football as any team in the league in my opinion, out with Celtic."