I recently climbed through that range to 630 or so. I tried to use one opening every time (Italian Game) and explore all my misses in depth in game review/analysis. I try to trade somewhat aggressively so that the position doesn't get too complicated (I tend to lose on time in those cases). I also do a lot of puzzles and aimchess. Sicilian was kicking my butt so I watched several "anti Sicilian" videos and tried the simplest ideas which helped.
Ah, interesting. So you mean that it is best for beginners to trade whenever possible?
I say no.
If you lose on time, there are some obvious answers: play longer time controls and improve your calculation skills (by solving puzzles). These will also help you improve your chess skills. Forcing trades in an artificial measure that will help you in nothing.
"Ah, interesting. So you mean that it is best for beginners to trade whenever possible?"
I still try not to do bad trades but I err on the side of trading if it's neutral, since a simpler position is quicker to evaluate and I tend to lose on time. But there are so many better players here; I'd listen to them.