In general, I would say that understanding what a good vs bad trade is... If you lose half your hp for that caster minion, was it worth it? Were you not punishing or poking your enemy laner let them get away free with cs when they might have been out of position? Is it worth tp'ing to lane if your team is setting up for infernal or a big teamfight? Basically, you should never lose something without getting something good in return-> thats the fundamentals of trading. This applies to microplay in lanes as well as macro play
In lane and in teamfights, know where you should be positioned. Squishy healer? Stand at the back and spam heals. Tanky engager? Stand in front of your adc and soak up taht damage for them. Balance that with knowing when to safely poke and you're good :)
A big thing to look out for is warding and where the enemy jungler is as well. The easiest way to do this is to 1. ward river/bushes whenever you can safely do so 2. keep an eye out for jungle timers and enemy ganks. at the beginning of the game you know where the jungler starts (usually) because the leashers usually get to lane late. From there you can basically figure out their path since strong early junglers like shaco and lee will likely do an early gank after clearing their first buff and before clearing their second. Another possibility is that they gank after their second buff.
-After ganks, you can usually see which side the jungler is going so be aware of that
-Every buff shows timers when it's close to respwaning now so if you see taht on your side of the map it's likely you'll get ganked soon so play safer and make sure your wards are up
You can also try deep warding to get a better idea of where the enemy jungler is.
Other than that, keep practicing farming and if you try to practice an be mindful of all that you should improve :)