Paraphrased from Quora
1. The confederacy should have tried and gained recognition as a separate country by England or France before the war started.
2. Not taken the bait of attacking Fort Sumter. Lincoln needed the south to strike first so he could put down a rebellion. Lincoln’s opponents could have used his aggression against him because there was popular sentiment to “let the south go, good riddance”.
3. Had the south baited Lincoln to shoot first, England or France might have had their reason to get involved and the North wouldn’t have had a rallying/recruiting point to mobilize around.
4. Not embargo cotton and make Europe break the blockade. Prior to the opening of hostilities, the South embargoed cotton, trying to create a demand in Europe. They wanted Europe so desperate that there would be no question of aid. Europe did something the South didn’t expect. They settled for the lower quality cotton available from Africa.
1. Stayed on the defense. Had Lee not gone to Gettysburg but instead dispatched a relief force to Vicksburg, history might have favored the South. Warfare during the civil war favored the defender as the tactics did not match with the new weaponry for offense. Lee could have stayed on defense in the East and had the resources to save Vicksburg/stabilize the West. Doing so would have changed the war as Grant would not have had his victory that got him promoted, the Mississippi would still have been open to the CSA and Sherman wouldn’t have been setup to march to the sea. All of which could have led to Lincoln not winning re-election and a peace treaty.
2. After the first battle of Bull Run, Washington, D.C. was virtually unprotected. A Confederate force could have capture the city and, more importantly, captured Abraham Lincoln. Probably no other leader could have managed the Trent affair, persuaded the Border States, enlisted the cooperation of the opposing party, assembled the remarkable cabinet he had and gritted out the war to its conclusion. A Union without Lincoln at its helm would have been a much weaker opponent.
3. If Kentucky had remained neutral and not had been forced to request Union assistance to repel the Southern invasion, there would have been no Battles of Shiloh or of Corinth nor the later siege of Vicksburg. The only other chance they had after this was to avoid losing until the Union populace tired of the war to the point that the Northern governors would force the Lincoln administration to sue for peace. While the Confederates did a pretty good job of achieving this objective in the East until first Antietam and then Gettysburg, they failed miserably in this regards in the West where Bragg’s Army of Tennessee was defeated or pushed back by clever maneuvering of the Union armies until his single victory at Chickamauga, which occurred too late in the war to have any effect on the will of the Northern people.
4. Fought a Guerrilla war or practiced scorched earth before Sherman did it to them. Win like the US did in the American Revolution. Confederate military strategy should have been based upon the strategy the Americans used against the British in that war. Namely, a Fabian strategy should have been the modus operandi, avoiding battle where no strategic benefit could be achieved. If surrendering territory was necessary to do so, so be it. Recall that in the war for independence, the Americans lost both their political capital (Philadelphia) and had their largest city (New York) occupied for the bulk of the conflict.
The south could have kept fighting after Lee’s defeat and made occupation such a headache that the North gave up. They basically won the Peace after reconstruction doing a whole lot less and one just needs to look at how the US occupations have gone in recent years to get an idea of what it could have looked like at home in the US. Imagine terror attacks in northern cities and the occupied regions of the south with no way of stopping them. This was proposed by Nathan Forest and company but Lee opposed them and surrendered.
5. The south actually making the war about states rights and freeing/conscripting slaves into the army in return for freedom early on (the British did this in the American Revolution)