I think you are off to a great start...making those small changes really does add up:-) I think the first step is finding a meal plan that works for YOU and some exercise...one thing I have learnt on FS is that no one meal plan works for everyone...its all trial and error.so do your research... check out the web and YouTube for ideas/options...browse through FS profiles and start conversations(people are always willing to share what they are doing and how its working for them- remember its THEIR opinion)
Some meal plans I have come across on FS include weight watchers,vegan Herbalife/shake programs, LCHF, Banting, Atkins,juicing 5:2 and tons of crash diets,etc
When I first started my weight loss journey... I started by reducing my meal portions, reducing my sugar and starch...I made small goals like eating healthy breakfast every day...once I got that right ...I added healthy lunch...etc. I believe life and food should be enjoyed so I needed a meal plan that allowed me to eat normal food...I didn't just want a "diet" but rather a lifestyle...something I can do forever...I also didn't want to feel deprived...So now I follow the 5:2 meal plan...where I can still eat the foods I like and still drop the kilos
All the best and hope you find something that works for you!