Direct election of the US president would be an improvement. Expanding the House of Representatives as originally formulated, or similarly, would help. Making the Senate reflect the population better by dividing populous states, and/or a statehood option for Puerto Rico and DC would help. Striking down gerrymanders would help.

More contested down-ballot races would help. No excuse for the parties to not have strong organization and candidate recruitment at that level. No changes to laws needed for this.