Considering trying Vegetarianism for two weeks!

Considering trying Vegetarianism for two weeks!
Hey there! So, as a result of recent studies regarding the environment and climate change, I've decided to try out a vegetarian lifestyle. All this daunting talk of oceans warming up 60% more than we estimated each year, discovering we have wiped out 60% of animal populations since the 70s, entering the 6th mass extinction event in earth's history and, since consuming so much meat being a contributing factor, i wanted to make a change. After discussing with my brother and dad, they agreed and wanted to join me so we are doing a two week change, just to test the waters.

I generally eat meat once every three days or so, I think, and I'm wondering if this lovely community has any tips for a noob for starting out. We are starting the next week and I'm gonna go shopping on tuesday. I need to eat pretty cheaply as well, as I'm on a budget.

Meal plans? Vitamin supplements that are necessary if I commit to the change? Substitutes? Things like that would be greatly appreciated. Thank you! :)