Having a plan is an excellent way to start a habit. Through making a plan you implement intention.
An implementation intention is knowing when and where to implement a habit. Implementation intention gives you clarity. You do not wait for motivation or inspiration to strike since you already have a plan to follow.
Making changes to habits is better at the beginning of things, say, the start of the week, month, or year since people are hopeful. A fresh start is always motivating.
Implementation intention gives you specificity on what you want to achieve and shuts down anything that does not add to that. Tie down your behavior to something you do every single day. This makes you practice the positive version of the Diderot effect by chaining small habits for the momentum that comes from doing an action leading to another.
Habit stacking allows you to create rules that guide your behavior more like a game plan of what comes next.
To create a habit successfully, have a specific and clear cue to kick things off.