Best way to learn bot lane is to support, I'm not joking. You learn by watching and seeing what the adc has to do, and what to avoid doing, and most importantly you learn the importance of vision and utility. When I was learning landing coming from jungle main, I used to pick supports with a lot of useful stuff in their kits (because as a jungler, you know the rough respawn times of red blue dragon and baron, and also how much cc can help in gaining an advantage on lane. I gained a knack for Threah, because literally every single ability in his kit is useful both aggressively AND defensively. From simple lantern gank setups, to flaying a mid q lee sin, thresh is an amazing support to learn bot lane with.
From there I started to observe what my adc was doing, and looking around the map, checking the map every time my adc last hit a minion (this is how I gained my map awareness for all roles, which is why I don't rely on ss/mia calls) and after few games of doing this, you learn how the lane works.
Some basic stuff: siege/cannon minions push lanes really hard and are worth the most gold, prioritise these over any other creeps when last hitting, as they give a large amount of exp and are worth 2-3 melee creeps in gold.
Melee minions are worth slightly more gold than caster minions, but have a lot less DPS than caster minions, thy. Also can take 2 shots from towers so they are low enough for you to last hit.
Caster minions are worth the least gold of all the lane minions, but they are the ones who really hurt your towers and YOU if you're not careful. These ones can be tricky to farm under towers if you have less than 90-100AD, as they can only take 1 hit from a tower, so what you need to do ( and this takes practise) is observe the red line from the turret, and try to attack the minion the tower is targeting before it attacks, so after the tower has taken its shot, the caster minion should be low enough for you (or your adc) to last hit.
Advanced stuff:
Turret Attack Prioritisation: If you are being attacked by an enemy champion who is within firing range of the tower, even if there are miniions also under the tower, the tower will ALWAYS prioritise the champion over the minions, but only if the enemy champion attacked with with a damaging attack (Nasus' Wither doesn't make towers go agressive as it does no damage, for example). If there is no enemy champion attacking you, and that champion is in tower range, even if you attack him, but he doesnt attack you, the turret will NOT target that champion (there are a few exceptions: Nasus Ultimate, Renekton Ultimate, and Sunfirecape Passive to name a few, to say if they get too close to you, the turret will see it as you taking damage from a champion and start attacking them) the tower will simply follow its natural order of killing minions. That order is: SIEGE/CANNON>MELEE>CASTER, always in that order, unless it was already attacking something else in which case it wont switch target until that unit is out of range, or dead. Remember, if a champion starts attacking you under your tower, the turret will switch to attacking that champion even if it was attacking something else!
Minion Aggro: Basically, on lane, minions will generally target the things closest to them, but they mostly prioritise other minions above all else, and since melee minons arrive to lane first, they are targeted first in most cases. However, like towers, if an enemy champion attacks you within the minion's attacking range, the minions will immediately switch to attacking the enemy champion. The minions dont seem strong, but this very mechanic catches a lot of people out early game, because caster minions really hurt (minions are OP, never forget that). There is something you can do to remove this minion agression onto you if you are being attacked by them, and that is to walk into a brush, now if the enemy has that bush warded, the minions will keep attacking you (this is good and bad, cos if you learn the bush is warded (ie if the minions keep attacking you while you're in there) you can tell your jungler that that bush is indeed warded so he doesnt waste his time trying to gank there. If it ISN'T warded, the minions will go back to killing the enemy minions instead, and you can just walk out of the bush and they wont target you.
Freezing a lane: this ones quite tricky, I have not mastered it yet, but basically, to freeze a lane is to make all the minions stay in one place on the lane (ie just outside if your tower's attack range) so you can safely farm without the risk of getting ganked. (NOTE: The lane with the HIGHEST DPS will push towards the opposing laner's tower, and vice versa) This is very hard for me to put into words, but basically what you want to do is MINIMISE THE DAMAGE YOU PUT ONTO LANE. This can be done in 2 ways that i've learned, 1) only last hit a minion when it cannot take another hit from other minions (NOTE: Lets say you want to last hit a melee minion, you also have a melee minion attacking it. normally the last hit window on lane for a minion from a champion is around 50-70 hp, for a minion to kill a minion, for example, lets say it's 8hp. when you want to freeze, you dont attack the minion until it cannot take another hit from another minion (in this case, 8 hp or lower)). The other thing I've learned to do is if you have caster minions attacking (this goes for towers too!), again wait for the minion you want to last hit to reach low hp so that it cannot take another hit from a minion, if you attack that minion and kill it as the caster minion's projectiles are coming towards that dying minion, you technically take those caster minion's damage off of the lane. sorry if that didn't make sense, but once you see this in action, you will understand, and I really wish I could record this to better explain what I am trying to say :(
Lane Trading: in a 2v2 trade, assuming this is on bot lane (ADC & Support vs ADC & Support) you should always focus the enemy who is locking down your ADC. Why? Because if you unlock your adc, you get your trading power back (again hard for me to explain, sorry X_X) Lets say it's Thresh Kog'Maw vs Tristana Leona. Leona jumps into kogmaw using her Zenith Blade and then stuns with Q, now right this second, your ADC will stop being able to deal damage, and will want to try and get away from leona, if you're attacking the Tristana, , they will either: (A) Tristana will rocket jump to leona who just dived past you to the fleeing kogmaw and kill him, or (B) the leona will switch to you and you will die. If you go for the leona, Kogmaw can stop focusing on escaping, and focus more on Attacking and returning the damage. Support is all about PROTECTING YOUR CARRY, as A Thresh, you CAN stop leona as she is jumping to someone with a well timed Flay, then keep her supressed with a hook (because you can start casting your hook DURING the flay animation, so basically she is a sitting duck.)
Hopefully my...attempt... at trying to write a guide is useful, sorry for the long wall of text (should I spoiler it?)