If you think about it, current politicians should be banned from giving paid speeches. When you are making $50,000 for a speech, that amounts to a legal bribe, when the entity paying for the speech wants something from you. Nobody is worth that much. This is a big part of how the Clintons became wealthy legally (to which, of course, must be added their de facto use of the Clinton Foundation as a piggy bank).
Former politicians should be banned from such activity for five years. Perhaps they could accept a delay between political favors and recompense, but five years is likely more than most would be willing to wait.
People go to the House and the Senate and the White House from jobs paying $200-$300,000 a year, and wind up worth $20-$30 million within 10-20 years. As a business proposition, as a pursuit solely of money and power, this is one of the surest bets going. There are many, many forms of legal bribery.
We need to denigrate the national government as a whole in its overall role, and importance, and perhaps one step might be to diminish immensely the perks of office.