The best way to do it is to have fair oversight of their elections. Not to take over their elections, but to help them hold fair anonymous ballot elections themselves.
Military intervention/violent revolution has a good chance of escaping the pot, but they almost always land in the firepit.
Ideally, I agree with you. Sadly I don't see how it can happen. The current dictatorship holds a corrupt power over the electoral service and they are not interested in negotiating any internationally backed supervision in elections. They know they'll always win with their BS elections so they continue to dangle it over the Venezuelan opposition's heads to keep buying more time for their regime. It's the reason why they've stayed in power for so long.
That and the huge payouts they offer to the military brass to stay under the dictator's thumb.
So no, sadly I don't see fair elections happening until the regime has been toppled.
Peaceful regime changes by time (dictator dies) or peaceful public protest may need a longer time to reach a democracy, but result in far, far less death, destruction and general suffering on the way. So i do prefer it, although it seems cruel. But history shows again and again that actually the slower but less destructive way is usually less cruel.
The Franco-regime in Spain beginning in the 30s basically ended with the death of the leader Francisco Franco in 1975 (1977 were the first free elections). The most suffering happened in the establishment of the dictatorship in the spanish civil war.
In the second Iraq war dictator Saddam Hussein was toppled by military action, was arrested and executed. The number of deaths among civilians are estimates between 100,000 and 600,000 (way less soldiers died). The destruction was immensely and many were wounded or fled. In the aftermath of the war the life expectancy severely dropped. The power vacuum lead to the strenghtening of multiple terrorist organisation and to the establishment of ISIS, which added even more death and destruction. Until today Iraq is in military conflict.
In South Korea happened in 1961 a coup by Park Chung-hee, who claimed the power for himself. He was head of the dictatorship until he was shot by his secret service in 1979. The military dictatorship endured a decade more until general Roh Tae-woo allowed for real reform and democracy in 1987.
Muammar el-Ghaddafi became dictator of Libya in 1969. He was toppled and killed in Libyan civil war in 2011. In that war at least 10,000 combattants were killed, although estimates assume a higher number. The war left the country unstable and lead into a new civil war in 2014, the establishment of ISIS in the country and terrorism. Over a million people are undernourished, another million fled the country. The situation is unstable even these days.
After the chinese emperor was toppled the chinese republic with one-party-system was founded. At the end of the 1920s general Chiang Kai-shek step for step obtained more power. Under his leadership the one party Kuomintag excluded more prior included groups, especially the communists. In 1927 he lead a massaker in Shanghai to exterminate the communists. This effectively killed all the moderate leaders and lead to Mao Zedong becoming communist leader. World War II and chinese civil war lead to the defeat of Chiang Kai-shek and he fled to Taiwan and let the Republic China exist ongoing on Taiwan. He lead the island dictatorial. Only after his death in 1975 his son reformed Taiwan slowly into a democracy. This process was very slow, only with the first presendential elections 1996 Taiwan can be counted as a full democracy. But while slow this process was mostly free of violence.
In the aftermath of World War II France lost control of it's colony Indochina. The reclaimed control over the south, but the northern vietnam retained it's independence. So 1946 it came to a war, in which France tried to topple the north vietnamese government and made it again a colony. This war ended 1954 with the french loss and the independence of nothern vietnam, Laos and cambodia and loss of control from France over southern vietnam. Around half a million people died in this war. Southern Vietnam stayed unstable after the war and the western influence was retained, with more and more the US taking the place of France. In 1964 the US lead an attack to northern vietnam to also gain control over the north. This war took another decade and lead to the death of another two to five million vietnamese people. Overall this attempt to topple the government was unsuccessful, even worse: northern vietnam gained control over the whole country. After the massive suffering because of the two wars that tried to topple the northern vietnamese government, the dictatorial regime of Vietnam lead in the following decades until today to economical upswing and to relative wealth of the people.
After World War II germany was split between the winners of the war. Eastern germany under soviet control became a communist dictatorship. While this situation stayed this for fourty years, a peaceful uprising toppled the communist government in the end and brought democracy to eastern germany in 1989, which lead to reunification with western germany a year later.
So yes, Maduro is bad. But as history shows us, a war is much much worse. It may take decades, but a peaceful resolution is preferable for the people of Venezuela.