How to Survive Early Game (First 10-15 min) (The most important part of this game)
There are only a things you need to focus on to survive early game and start rolling into mid/late game.
**Don't die. **
Obvious I know, but even when obvious, far too many people die before the 10 minute mark. If you can last until then without dying then you are playing your lane correctly. There are rare situations when this its okay to die, very rare. This rule is so important so so so very important. DO NOT DIE.
Last hit.
CS, Farm, Last hitting. The 2nd most important thing you can do (second to staying alive). Melee Minions can take 2 hits from a tower and then one AA (auto attack) Caster Minions require one AA, one tower hit, one AA CS is far more important than kills, if you can get a kill take it but if you are focusing on kills so heavily that you are behind 30cs you will hurt later in the game.
Understand the match up in your lane
Counters do exist in Leeeeg O Lemons, and they aren't called counters because they have a 'slight' advantage over your kit. A counter is typically a match up that 3 out of 10 times you win. This is of course assuming if you are similar skilled with the characters being used. Counters usually stop your entire character from fighting at 100%. Look up a website (or phone app) and watch out for your counters, if you are countered in lane play extremely safe. You don't want to die early in the game. When you are killed by your counter it only gets harder if not impossible to handle alone. (no surprise there)
Runes/Masteries/Starting Item/Summoner Spells
Your these play a big role in your early game. You should have multiple rune pages for your main character to fit various situations such as going against a tank, magic damage, physical damage, stuns, etc etc. Masteries are usually unchanging, only on certain characters do you change your masteries frequently. I personally have no saved mastery page and remake my mastery page every game so I don't forget what I am using. Sometimes it's good to change up your starting item. If you are going against Swain, it might be a good idea to start with boots. Going to trade a lot with people? Buy some health/hpregen or raw damage. Summoner Spells should be considered, it's good to have a TP/Exhaust/Ignite/Heal/Smite on your team. Don't be afraid to change your Summoner spells to help the team out. Examples are if you have a Rengar top and he takes ignite. Don't be afraid to take tp mid. tp mid is sometimes more effective than ignite. Understand the situation, don't do things just because you did them last game.
"I am behind"
If you die first in lane there is a 99% chance you are officially behind, don't let your pride swell up saying "he just got lucky, it won't happen again". If you think that way it WILL happen that way again. If they are zoning you (not letting you cs) let them zone you and politely ask your jungler for a gank, nobody wants to gank for a whiny bitch. Staying alive is more important than farming remember that. You can farm later, you can't take back a death. Slowly farm, carefully defend, until you catch up to the enemy team.
LASTLY I MUST SAY, BECAUSE THIS IS THE MOST IMPORTANT RULE DO NO DIE.
Good luck in your journey through the good ol Leeg O Lemons