I find it helps clean up code a lot to use early exits. Consider using:

sub someSub {
    if (some condition) {
        ...
        return;
    }

    if (some other condition) {
        ...
        return;
    }
}
[download]

instead of:

sub someSub {
    if (some condition) {
        ...
    } elsif (some other condition) {
        ...
    }
}
[download]

Despite taking a few more lines the first version makes it much clearer what the conditions are for some task to be performed and makes the exit conditions much clearer. This technique can often collapse deeply nested conditional code to a single level.

The same technique can be applied in loops to take early leave of the current iteration (using next) or terminate the loop early (using last).