As for rain....XD I dunno looks like you have already gotten some good suggestions...My only sugesstion would be to look at a reference of rain and try to recreate it using traditional methods....or to just go crazy with it XD watercolor splatters, or painting a light shade of blue, letting it dry a bit, and then going over half of it with darker blue with a dry, rough brush. Of course, that kind of background I just listed probably wouldnt work with the angle you've got going...
And obviously you would want to practice getting used to doing rain before putting it to use in that picture. Looks good so far! Can't wait to see the completed picture.
I kept trying on it, but somehow nothing I drew on seperate paper seemed to work. I guess I just realised that I love white acrylic and tip-ex too much for my own good. LAWL. I went mental with it. I have to admit, my hand aches now after all of those lines for the grass and rain But I think it was worth it. LAWL. I'm going to try and do a few black and white pictures perhaps trying to make rain work. See how they turn out. Perhaps I'll be able to teach myself. After all, I normally do and things turn out fine. XD
Well If you are gonna put rain on it you shout try to do some lines with blue ink and the back ground have to be with blue and dark colors and some white, no to much.
And if you can try to mix some blue and withe lines to make the efect that is raining and do not forget that if L have an umbrella you have to make the impresion that L is not geting wet.