Well I don’t really, and I want to know if they are really worth to invest. I’ve tried a few times, but not legitly. I mean, if you say you’re going to wake up at a certain time for WBTB w/o an alarm or that you’ll have a vivid or lucid dream, has it helped you?
Thanks:)
WBTB usually produces some sort of dream, but I usually miss the sign and have an FLD or ND and they arent always vivid 
. Mantras I rarely use them and need to pay closer attention to the times I do to get some sort of result of how well they could work.
Auto-suggestion does work, but you need to be bussy with it actively. The more senses you include in your Auto-suggestion the better it works. This is because you have more senses recording your intent. Although I have never really done it during WBTB I assume it would work better.
When I use autosuggestion I do the following:
-I write down a mantra of 3 lines. In those lines I write down the things I want to happen. (example: I will have a lucid dream tonight. I will fly in my dreams tonight. I will remeber my dreams. )
-next I record myself saying those lines.
-then I start writing two pages full with the mantra while listening to the recording on loop, mouthing the sentences, and thinking about the intent actively. (I think it would work better just saying it out loud but it isn’t really possible for me because of fellow housemembers 
).
I think the easy thing about Auto-suggestion is that anybody can do it. The succesrate isn’t excellent but doing it takes almost no investment of time. And usually my Non lucid dreams are more vivid when doing this.
And the most important thing is, if you don’t feel like doing it one night you shouldn’t. Doing it half-heartedly doesn’t do anything (in my experience).
Hope this helped 
EIDT:
It’s useful to also do these autosugestion exersises a couple of times during the day. at least twice will really make a big difference. You can do it while going to the shops, going home from work while cooking. Although you should always pay attention to your suroundings, don’t want you to get hurt. Do it more like singing along with the radio.