How many to chain at the beginning of a row

[Knitting nana]

I am new to crochet.  I come from a knitting background.   This chaining at the beginning of a row is a foreign concept to me.  The question is: how do I determine how many to chain at the beginning of a row? Right now I am making a blanket with one sc and one hdc.  I am chaining one but now I am second guessing and thinking maybe I should be doing 2 for the hdc.  Is there a rule to know how many to chain?

[bgs]

Yes often but not always you ch 2 for turning chain for hdc.  The turning chain is used to get your row started at the right height for stitch used in the new row.   This explains turning chains, how many to use, where to place the first stitch, and how they are counted. Its very important to know where to place the first and last stitches of each row otherwise you make unintentional increases/decreases.  Its very easy to mess up even after crocheting for many years and knowing this.  The best way to catch it early is count stitches as you complete each row and fix it then.  Otherwise you could be faced with pulling out several rows when you notice a side getting bigger or smaller. Also there are alternatives out there to use as your turning chain because on the taller stitches using chains leaves a gap.  This is another helpful article.