Germany not taking Alsace and Lorraine in 1871, and following Bismarck gut, should be a necessary start. French revanchism will still exist, but would be much more managable, in my opinion.
Then, you could increase colonial tensions between France and Great-Britain with a Fachoda*10 and similarly increase German antipathy towards Britain, for example using the Boer war. If France and Germany at this point of the late XIXth century both consider Great-Britain to be their greatest threat, which she is not in reality, but it could be felt that way, then you might get a France/German anti-UK alliance.
This would be a diplomatic disaster for the UK, which would require Great-Britain to get to terms with Russia in the Great Game much earlier than IOTL. Then, if both Russia and Great-Britain apply sufficient pressure, they could coerce/bribe the Ottomans to join their side in a potential alternate-World War.
This leaves Austria, likely still allied to Germany in this scenario, but could be convinced to remain neutral when Austria considers she'll have to fight on two fronts (Russia and the Ottomans). But with full German support (not occupied with the war against France), they might as well decide to fight it anyway.
And Italy is either neutral as in OTL, or joins France and Germany/Austria outright. No way they would join against both of them and also fight a 2 front war.
So we have a scenario GB/Russia/Ottomans vs France/Germany/Austria. The GB alliance is going to get crushed on the continent, Germany defeated Russia on her own OTL, with French support, they cannot lose this. And Austria+France should be a match against the Ottomans. The question is on the colonies. The BEF can probably be deployed anywhere, but French colonial troops are not to be under-estimated, even without the support of the mainland.
Basically, this world war is almost a Napoleonic rerun, when the French-German alliance dominates on the continent, and GB rules the seas and snatch colonies left and right, trying to provoke economic collapse. It's not sure it will work this time.