One of the tips to make it better to stop smoking is by finding a replacement for cigarettes that you can keep inside your mouth or hand. In this way, you can gradually change your cigarettes with something else. A drinking straw could work, or even a bit of a pretzel or candy could serve as an effective change.
When the anxiety about gaining weight could be the only thing keeping you back from stopping, you need to know that increasing weight isn't inevitable. No weight is gained by several former smokers if they stop. That said gaining a few pounds is still far healthier than continuing to smoke.