OK, first off it does not matter the order in which the cords are connected. The same current travels through each cord, and the voltage drop over each cord is independent of its location in the string. It makes sense to put the lightest cord at the end just to have the most flexible cord closest to your tool, but electrically it doesn't matter.
As for current capacity, there are two things to consider: ampacity and voltage drop. Ampacity is simply the maximum current the cords can handle without melting. In general, 14 gauge cords are good for about 15 amps; 12 gauge for about 20 amps and 10 gauge for about 30. Needless to say, 16 gauge cords are best avoided altogether. However, the connectors on most extension cords limit them to 15 amps, which is why a 10 gauge extension cord will be marked as "15 amps", even though its conductors can handle much more than that.
The second thing to consider regarding current capacity is voltage drop. To get an exact answer, you need to calculate the voltage drop over each cord at the expected current, then add up all the voltage drops and decide whether or not the total drop is acceptable. Most folks aren't going to bother with all that, but that's the only way to get a definitive answer.
A general rule is to use the heaviest, shortest cord possible. Let's say you need a total length of 150' and you have four cords: 2 each 10 gauge 100 ft., a 12 gauge 100 ft and a 12 gauge 50 ft. Using the two 10 gauge cords will give you the maximum ampacity. However, you will get roughly the same voltage drop using one of the 10 gauge cords with the 50 foot 12 gauge cord. And you will get the greatest voltage drop and least ampacity using the two 12 gauge cords.