Top of the list is "Plant something and nurture it". I must admit that although I'm very good at planting things I'm not so good at the nurturing side. I have a tendency to lose interest once something has sprouted, especially if it needs constant repotting. However I do get an enormous feeling of satisfaction from seeing a little row of pots all full of seedings.
I find it amazing to think that one day you can take a tiny brown seed which has been kept in an old tin in the garage for a couple of years, put it in a pot with some soil and water, and a week or so later you have a bright green seedling, stretching up towards the sun.
My biggest problem is that I tend to go a bit mad, for example by planting about twenty tomato seeds. I can't bear to throw out the weaker seedlings, so I continue to grow all of them, meaning that I'm constantly running about repotting into larger pots, filling windowsills with huge planters, and struggling to keep up with removing the side shoots. Then we go away for the weekend, they don't get watered for a few days, my poor spindly plants all die, and it's a relief to chuck them all in the bin and promise to try harder the next year.
Now that I've got a Harry to help me out, let's see how I get on this year!