I made a cynical-sounding resolution to be less of a 'nice guy.' There's nothing inherently wrong with being courteous, polite, thoughtful, etc. However with experience I've unfortunately found that niceness is often taken for weakness. I grew weary of being everyones' lowest priority, having to defend myself in challenges so often, and having to fight to get what I rightfully deserved in the first place. So I made a resolution to be more bold and demanding, to take instead of ask, and even to be a bit of a jerk when the situation demands it. That sounds laughable but so far it's working and I haven't even had to dip into jerk-mode yet. I've been in fewer arguments recently than in the weeks preceding. I've had fewer people try to take advantage of me. I've gotten reductions on dinner bills, free items at stores, and at work my shop is hopping with productivity. I no longer ask things like, "Excuse me, X, do you know when those materials will be ready?" I say, "Listen, X, I need those materials. I asked you for them already last week, so now I need you to make it happen."
Hey this is not laughable. I know personally how much not being assertive can hurt both relationships and life goals. It's good to recognize it and try to be self-reflective. You don't have to even be a jerk! You just have to be direct. There is a cliche that I've had to use, but has been helpful. Whenever I feel myself pulling backward toward being passive "Mean what you say and say what you mean" in other words, be mindful of what you want and ask for it. Good luck!
There's nothing wrong with being assertive, especially when you're spending money.