Advice from a begginer

Ok, I have been following a lot of articles, blogs and websites about gardening and I tried to use some of the advice - not all of it good.
So here are a few of my tried and failed or successes:

- seedlings - since I only use a few pots, I don't need a large amount of plants or seedlings. I use a normal desk lamp and a plastic container, plus egg cartons to sprout seeds.

Now, the advice I followed and I should't have - DO NOT PLANT the seedlings with the carton. I did that and the seedling barely grew. The ones I took out of the carton are twice as big.
The carton-planting might work in the garden, but in a container, you need to remove it to promote root growing.

- seeds - the first time I planted store-bought seeds, I planted too many of them and they all sprouted - which means I wasted a lot of them, since most of the time I had to pinch off the plants.
So now I only plant 3-5 of them in a carton, just in case they don't sprout.

- watering and fertilizer - no matter what type of soil you use, plants in containers dry up fast, so I spray water on them every day. On the soil, not the plants! Most of the plants do not like water on the leaves and it promotes fungus, so try to avoid wetting the leaves. This means choosing bigger pots so that there is room. Also, I add a small amount of fertilizer in the water (half of the recommended dose) because the nutrients in the potting soil are exhausted after about 2 months and the plants need them.
Also, I water them with tap water that was kept in bottles for at least a day to remove the chlorine.

- soil - I use the cheapest version of potting soil, but I add slow-release fertilizer every 3 months to it. There is a granulated type that dissolves in time (I have the one recommended for strawberries, but it works for anything).
I also have a few pretentious plans :) I bought a bag of orchid soil for an orchid and now I use the rest of it for acid-loving plants (the rhododendron, the camelia, the blueberries and so on). I mix it with regular potting soil because it's acidic so it lowers the PH of the mix. You can also add a spoon of apple vinegar in a liter of water and use it for them (trick I learned from a florist).

- pots - I try to not spend too much, so paying a lot for a big pot is against my nature :) I use plastic buckets and garbage cans for the plants that have deep roots and small buckets (from yogurt and sour cream) for others. You just need to wrap them in colored paper or even duct tape to make them look pretty. The only rule is to poke holes in the bottom to allow water to drain.

That's about it so far :)
I'll add more later.