I am on the border of bronze/silver. Whenever I am in a zerg vs. zerg situation, there is always at least one battle between groups of zerglings. often, this will happen at the beginning, with small groups of lings. When 4 or 6 lings are fighting each other, it looks pretty frenzied and is hard to follow which ling is attacking which ling. Should I be doing anything to micro my lings? Does focusing down one of the enemy lings work? I know if I had a line of 4 roaches vs 4 roaches, I would focus down one of the enemy roaches at a time. But is that effective with lings? Could 4 lings, properly micro'd, stop 6 lings? I imagine that as the groups of lings get bigger this would matter less, as only so many attacking lings can surround one victim ling.
To win against 6 zerglings with just 4 zerglings is almost impossible unless you have really, really good micro and the other guy doesn't even look at it. But if you focus too much on the battle you will lose focus on your macro, so you might forget to build more drones or zerglings which hurts more than losing a few zerglings.
I would retreat if possible, but if the fight is in your base then get 2-3 workers into play or just run circles until you have more zerglings or a spine crawler.
If you really, really just want to win that battle it helps if you split your zerglings and attack from 2 sides and focus fire. Retreat the wounded zerglings and attack again if the enemy stops attacking them. Try to circle the enemy zerglings one by one. You will most propably still lose, but you might kill 3 instead of just 2 zerglings.
You don't want to over micro your units. Sometimes getting maximum DPS is better than micro-ing your units around. You also don't want to engage in a battle you know you can't win i.e. running head first into a group of zerglings that out number your zerglings. If you only have 4-6 zerglings use them to scout and invest in speedling research before you harass.
You mentioned that there is always a zergling vs zergling battle. If this is the case when you are attacking their base you should run around for scouting info and then fall back. Do not waste your lings and minerals by engaging them at that time. If they are attacking you, fall back to your queen so you have the advantage.
Also, if you have Zerglings and a queen, don't panic and attack with your drones too. This will make it fair game if he uses attack move and your drones can be targeted. If your drones continue to mine he will be forced to either attack move and let the AI attack your zerglings/queen or he will have to single target your drones in which case you will do far more damage to his force than he will to your mineral line.
The best way to micro in this case is to keep your group of lings together, and run away from his group. If they are equal speed you should not have trouble keeping away. To micro lings you simply abuse the automatic AI.
When he attack-moves, run away. His lings will continue following your lings even if they will never reach them because you are running away.
When he simply tells them to move, you attack him. His units will not fight back while just moving.
When he force-attacks a single unit (other than your lings), attack his lings. They will not attack back until their target is dead.
When he force-attacks a single one of your lings, separate that ling out and attack his lings with the rest of yours.
The basic idea is:
- retreat when his lings are heading for your lings
attack when his lings are not heading for your lings
The main point of this is to delay until you can reinforce your army.
Zergling micro matters less against zerglings in an open field, because there isn't as much maneuverability room. Just a general attack move is a good idea. It might be a good idea to pull damaged zerlings out, but it is hard to do quickly, because they don't last very long.
I think 4 vs 6 is a lost cause, but jumping in and out of battle with a nice line might do the trick. Having speedlings would definitely help here.
On lings vs lings battles (and almost every ling vs anything battles) what matter most is that all your zergling can attack at the same time. When you have a small, dense ball of zerglings, only those in the outer shell will be able to deal damage. The best way to win these situations would be to spread them in a line and surround your opponent small zergling ball. This will allow you to maximize the number of 2v1 your zerglings will take on. This is a good strategy that you can scale up to any number of zerglings/zealots