The think that I try, .. and most often fail, .. to do when I'm laning (I'm more often a jungler) is to look at the mini map every time a new minion wave enters the lane. That means I should be looking at the mini map at least once every 30 seconds. It generally takes about 30 seconds for a champion to walk from one lane to the next if they are walking down the river.
What you are looking for is how many enemy champions are showing on the mini map. Lets say you are playing top lane and you are pushing the minion wave into your top laner's tower with them under it. When you glance at the mini map you can only see the two bottom lane champions. There is a chance that the enemy jungler and / or mid laner are coming top to relieve pressure for their top laner.
This is not always going to be the case, but simply not knowing where the enemies are, means you COULD be in trouble.
Alternatively, if you are in the same sceanerio and you can see the mid laner, adc and support are all in their respective lanes, and you know the enemy jungler was recently spotted on the bottom side of the map, you are fine to continue to play aggressively.
If you are over extended and you notice that there are no enemies showing on the mini map ... RUN!