Hi and welcome to KH and to knitting!
If you knit all the rows or purl all the rows, you make a garter stitch fabric which looks the same on both sides. Either way you'll produce the same end result.
As you say, if you do stockinette or ribbing you'll see the difference between the knit side and the purl side. For these stitch patterns, you're knitting on one side and purling on the other side (or alternating knits and purls).
Even tension is something that comes with practice for both knit and purl stitches. Trying several methods is a good idea that will help you find a method that is comfortable for you. It may be a combination of purling by one method and knitting by another. It sounds like you're well on your way, trying new things and playing around with the stitches. Enjoy learning and practicing!