I bought 2 Firepods and while that was cool I probably would have bought something better like one of the Focusrite units with adat and a Behringer ada8000 instead to get 16 inputs. Would have been able to upgrade more gradually and probably would have had better quality from the get go. When I did upgrade I had spend a few grand to get a full quality set-up like I needed.
I didn't get monitors for literally a few years and now I would definitely have gotten something better than a hi-fi much earlier on. I got adams A7's as my first real monitors and the difference it made to my mixes was much larger than I expected it to be. Kicking myself for not getting something better sooner once I realised it was the reason I was having the same problems with my mixes.
No real plugins I would feel I've benefited from I wouldn't have had starting out, I know what I'm doing with them alot better now and thats where the real difference has been. It takes time to learn how to make a compressor work the way you want it to and EQing is the same, when a mix is being done that's 75% of the tools for the job there and I still use stock/free ones all the time.