It is quite easy to increasing & decreasing in Tunisian Crochet
There are 3 ways to increase in Tunisian Crochet.
At the start of a row. Start in the 1st vertical thread not the 2nd
In the middle of the row. A loop is pulled through the gap located between 2 vertical threads.
At the end of the row Before working through the combined vertical & horizontal threads, and addition loop is pulled solely through the last vertical loop
Standard Return Rows are worked in each case.
A single loop is pulled through 2 vertical threads
A standard Return Row is worked.