Fast expansion is a key to success - land is power in this game, so practicing how to recover your economy can pay a ton of dividends as you get better at the game.
I think it's great practice to expand to the point where you're running 0% research, and try to crawl back out of the hole. As I was learning monarch & emperor levels, I played many games where I would expand or war early on, and be barely making money or even losing money at 0% research, and learned how to come back from it. I experimented a little bit, and sometimes played throwaway games where I would purposely go into strike.
You'll be a much stronger player long term if you can learn this skill. The most important points are getting to the key economic techs - alphabet (build research), currency (trade route), COL sometimes (courthouses), monarchy sometimes (higher happy cap), calendar (if you have key calendar resources). Also, trade extra resources for money after currency if you don't need them - every little bit of gold counts. War can also help if you have excess units from another early war - I remember a keshik game where I was losing money at 0% for about 50 turns straight - didn't matter because I kept conquering cities to take more gold.
You can slowly get your slider back up, and be running at 50-60% after awhile - with more land, that's a much better scenario than running 80-90% with very little land.