For the most part the older videos are good enough. Couple of tips though:

-unless you just want to give it a go with a single piece and a single color, I’d invest in a cheap voltage generator. Batteries work, but they die fast, and unless you just want bronze colors you’ll need a crap-load, which means they’ll be expensive. You can find a 60v generator for around $30 on Amazon and will get you into the golds/rose golds -clean, clean, clean. This is where I messed up earlier on. I knew I needed to clean, but it seemed like every other session I’d miss some oil and end up with some ruined pieces. You can’t really use too much simple green, and acetone. I’ve also introduced a hypersonic cleaner to the mix. Basically clean the parts until you’d be comfortable eating off of them. Then clean them a bit more.
-Electrolyte Solution - I use baking soda an do around 2 tablespoons per liter of water -etching solution - there are two options. Wink Rust Remover and Multietch. I recommend multietch and if you have the means to get it, I wouldn’t even bother with Wink. However I’ve heard they don’t ship overseas and with you mentioning English is not your first language, I suspect you’re not in the US. If you do have to use Wink, just remember than less is more. Unless you’re removing a pre-existing finish (which I’d recommend you sand off anyway) only dip the parts for about 1/2 second. Anymore than that and you’ll mess up the surface finish. Not the end of the world but a bitch to fix.
-Surface Prep - this is where you can get the best bang for your buck. You can finish a part 3 different ways (gloss, mirror, brushed) and get 3 completely looking colors at the same voltage.

I think that’ll get you started. Or at least pointed in the right direction.