yeah the industry opener is kind of a mandatory detour for an imperialist venice

. Besides that, I see that mixing up works well with the third policy block for many people. I should try it more, usually I do some opnener dipping with fealty (when going for another tree with a religious civ) or artistry (when going for another tree but with a GP dependent kit, like ceremonial burial). I think I once took both before staecraft, with Byzantium ... I also had very good results with opening tradition before authority with Rome, to give my capital a head start. But those were on emperor difficulty. I suppose the earlier the mixing, the costlier the delay of a finisher in terms of snowballing, thus why later mixing is more forgiving.
And without mixing trees, but doing unusual combinations of full trees. I wonder what is the most unusual? I haven't tried something like tradition-artistry into imperialism and domination yet. If you have a unique unit in renaissance, it can be good to stay tall and cruise asap towards imperialism. It typicallly works extremely well for me with England, but of course I would pick statecraft... With that sort of artistry-delayed warring, indeed maybe assyria could do the trick, to maximize great works before full scale war? The tricky part is having little use until then of the UA besides oportunistic, isolated conquests. I think the strategy would make sense with France too (first develop to have high base yields to which apply the UA percentage, maybe with a golden age monopoly), but same problem, keeping-up without UA. Maybe the best candidate would be japan, as it doesn't need to conquer, only to grind.
Then there is even further delay: tradition-artistry-rationalism into authority... of course picking an ideology is sometimes purely for diplomatic reasons instead of a well designed synergy. Korea maybe? Patiently waiting for logistics artillery? But with that kit you only need to take out a rival, then you would win before you can achieve domination.