Stickers on the car and remove disc, how best?

Hello, I will prepare the smart for an acquaintance because he wants to sell it. Of course, this also includes the stickers that have been on the car for a while ( D=P=CH=MOD= / Smart / veb-kalender-kombinat.de ) remove. I had already removed a sticker on the front window, that was already a real …. work. I thought so, I will remove the sticker on the disc with a glass scraper. I chose 2, once the CLICK or the CLICK. Which of the two do you think is better? With the stickers on the paint I am still a bit unsure or afraid, I have never done that before. I have already watched several videos, since the stickers were always warmed and then gently removed. Finally with a little dilution remove the glue and what I do pollute anyway!?