There are so many options available right now, from eco-friendly (online) stores offering to plant a tree with a purchase, to search engines like Ecosia using their profits for good, to a wonderful app called Treeapp.
It's such an easy way to have a tree planted, and you can even choose where that tree will be planted! All you have to do, is read three little blurbs about a wonderful sustainable business every day and voila, you can plant a tree. I've started to follow some amazing eco-friendly small businesses on Instagram because of Treeapp and I must say it's an absolute delight.
The app is getting so big now, that you have to be in early (before noon usually) to be able to plant a tree for the day, otherwise they're at full capacity and your personal tree count doesn't go up. You can input a goal towards you will work, and the app will tell you how much impact you've made per week, month and year. I started planted back in May and have got 125 trees under my name so far, making up for 61% of the carbon emissions I wanted to offset.
I added in my personal carbon footprint (that I measured through Bulb's calculator) from last year and this year, as this year is my non-traveling, non-buying year, but last year was crazy with moving house, buying furniture, getting married and traveling lots.