You'll get good games when you get better.
There are a lot of moving parts that intertwine that you can improve in league.
Look at your positioning, map awareness and decision making. If you work on these you'll get caught out less, be ready for engages and start better fights.
Positioning: Where are you in relation to enemies/allies, minions and terrain near you at all times.
Map Awareness: Can you see all the enemies on the map? If not, where might they be? Wards.
Decision Making: A lot of things go into decision making. League and other games have a lot to do with decision making big and small. A specific example, you're in bot lane, enemy adc is alone, is the enemy support in the bush or did you just see him on the map roaming around mid or top? If he's not in lane, you can probably get aggressive and take the 2 v 1 against the enemy adc.
Another example: If you're pushing a lane and hitting the enemy turret alone. If you see four enemies top trying to catch your singed up there you can probably make the decision to keep hitting the turret. If you look on the map and see two enemies and three are missing you probably should make the decision hit the turret a few times then back out.
Some simple examples you probably have a good grasp on I know.
Next up. Your CS, Runes/Masteries and Items.
CS: Making sure you're last hitting, if your lane opponent leaves lane and you're not following to counter roam if they roamed. Push in to deny xp/gold to the tower.
Runes and Masteries: Making sure they're what you want in your situation. If I toplane against a tank I usually take teleport instead of barrier or ignite and more defensive runes and masteries because it's going to be harder to all in a tank and get the kill than other champs.
Final: Knowing your champ (spell combos and power level.)
These ones are really just playing a champion, and getting to know what limits you can push, how aggressive you can go in because you get a feel of what your champion can do and what their power level in any given situation and matchup, as well as what you can do in duals or teamfights.
Another helpful tip. Aim to improve first, and win second. You may have lost, but are you learning from your mistakes and are you improving? This isn't to say not try to win, but that even if you lose don't get down on yourself, find out what you did wrong and correct it.
A lot of this is easier said than done, but good luck out there.
