I have smoked for over a decade (can't tell for certain when started regularly), I tried quitting 5 or 6 times.

Last (final) time I quit learned a valuable lesson - it's not so much how you quit but how you prepare mentally.

Nicotine is almost entirely in your head. Physical withdrawal for smoking is quick and rather easy so main thing is:

Ask yourself what do you think smoking gives you. Understand that smoking has no positive impact on you.

Only when I understood that there was no reason to smoke - I really stopped smoking.