Layering is simple technique to use when putting outfits together. The main rule to remember when layering is proportions, because you want people to see the different layers. Always be aware off lengths, cuts and colours. You can layer almost anything from tights to t-shirts!
If you are layering tops be aware of the neckline and sleeve lengths. I started layering as a kid after I saw Avril Lavigne wearing a band t-shirt with a 3/4 length sleeved top underneath, I was a big skater kid haha! I still think it looks really nice on some people and if you think layering tights or t-shirts with dresses for example, this is a great look!
I have seen a good few people looking good in low cut black/white t-shirts with a coloured string top underneath. If you're not as comfortable doing this, you could always pop a simple waistcoat over any top, one celeb who always does this and looks amazing is Cassadee Pope..
When layering tights, it's pretty simple. Wear a solid coloured pair first and then put a fish-net/lace design over.. or any other patterns/styles of tights you can get that would show off the bottom pair of tights!
Layering lace over threaded tights also works lovely as seen here;
This is by far my favourite way of layering! If you have any fancy dresses, you feel are too fancy to wear just going to the cinema or whatever, you can make it more casual by layering it up by adding a t-shirt underneath. It always looks nice when I see people wearing floral/patterned Summer dresses with a vintage-look t-shirt underneath! It's a really nice festival look.
Layering is always best in the Winter, as the more layers - the warmer you are! You can wear any outfit you like and transform it by just simply adding a nice jacket/coat over it. I would recommend getting a style of jacket that never goes out of style e.g. a trench coat. They can transform any outfit, into something amazing!