Efilnikufesin,
you will always get various advice as to which methods are ''the best'' and it can become a bit confusing sometimes, especially for newbies. You will rarely find someone who has trialed and tested all methods and thus most people will show you the only method they know, been shown and have used. Yes tethered self-launching and self-landing methods work great and are pretty safe if properly executed, but the big downside is they offer poor versatility as you need a very strong anchor point, lots of beach space, the right wind direction, etc. things that are obviously not always available.
As a beginner, the first and most important step is to get familiar with the safety system your kite uses and perform a few ''Emergency self-landings'' on the beach or even better in shallow waters. Unfortunately very few instructors will teach this in lessons. In my opinion this skill is the cornerstone of safety and independence of every kiter.
So, once you've done a few of those comfortably, you can attempt ''advanced self-landings'' as per my Youtube video showed above. The key in these methods is that you are always
detached from the chicken loop before attempting self-landing. Don't let anyone convince you to attempt self-landing without detaching from the chicken loop first unless you want to get into an accident and damage your kite. By detaching yourself from the chicken loop you are essentially in ''safety mode'' so if you fail to have the kite rest in a secure position you simply carry on following One safety line hand over hand to the kite as shown in the emergency self-landing video. Had an example just yesterday when someone attempted to self-land without detaching from the chicken loop first, failed, and the kite powered up and slammed into a 13 year old kid....

Self-Launching is definitely the most advanced skill here and for this one I would recommend you get more experience first. Lots can go wrong when attempting a slide-launch/drift launch
even to the most experienced kiters out there. The more wind and less space/more obstacles you have, the more dangerous this is. Again the key is to be as safe as possible and running through a safety checklist every time (see checklist at the bottom of the self-launching video). When you're ready for self-launching, first
try them in low winds (10-15 knots) and gradually attempt them in stronger winds. In anything above 20 knots, you MUST ensure the trim strap if fully pulled in AND that you
keep one hand on the chicken loop quick release. this way if anything goes bad you can respond very quickly and recover your kite
BEFORE you get dragged. To add to the complexity of this, every kite reacts a bit differently to self-launching, so it's also about getting used to the behavior of your kite as well.
Hope this helps,
Happy kiting and remember it's always safer to get help from someone and to always get a huge amount of clear downwind space when attempting any of these methods.
Christian