Ive played a few times as SU, and I dont bother with the upgrade slider in the beginning. Generally since there is a lot of dissent, I keep all my IC in production and consumer goods. I found that your industry gets a huge boost after about 1 year when your dissent is zero.
Basically my plan is as follows for single player:
Build IC until 1939
Get dissent down to zero ASAP
Dont kill the generals (yes it hurts the dissent, but helps in the long run)
Organize all the mobile units (tanks, mobile infantry, cavalry) into several units without slow 1918 infantry
All the while I am moving towards standing army. (Usually events unfold so there is no need to mess with hawk, or intervention due to triggered events)
Once you have moved a few tics towards standing army, your dissent is zero, and most of your industry is completed, I would then begin to upgrade mobile units using the prioritize button.
After I start occupying territory, I will move towards open society to help with the partisan problem.
Messing with the left and right aspect helps if you want to try and ally with the Axis. However, moving SU towards right hurts when it comes to ministers; there are many who disappear and you will find the choices under a fascist regime limiting. If want to go Axis, I would also suggest spending more time on researching Air and Naval units because the allies are more of a threat in those areas than their land units.
Im sure most of what I said is similar to earlier posts, but I hope this helps.