Hi Rammy, that looks like my 109E, from the page header
It is Adolf gallands mount sporting an early trial of the later war grey scheme, that was to become standard. The undersurfaces and fuselage sides are RLM76 Lichtblau (light blue, actually a light blue grey) The upperwings and fuselage spine are in a splinter scheme of RLM 74 Graugrun (grey green) and RLM 75 Grauviolett (grey violet). The mottle on the fuselage sides is RLM 75. The cockpit interior, wheel wells, inside the gear doors and the main gear legs are RLM 02 Grey (a grey green primer). The main wheels are gloss black. The cowling and tail are in RLM 04 Gelb.
The pictures in that link aren't the best I will put some better ones, if I have them, in my own gallery. You can access that by clicking the "My Photo's" button, at the bottom of this post.
For the mottle, like Phil says, you really need to use an airbrush and then it takes practice. However this mottle is quite specific and, with care you just might be able to achieve it with a brush. You could never match the subtle effect of an airbrush though. Which 1/48 Bf 109 kit are you building. Mine was Hasegawa's, of which there were several versions. If you are building the Tamiya kit or a different version of the Hasegawa kit I could scan the instructions for this scheme and let you have it, if you like? just drop me a PM, click on the "message" button.If you want any other info, just ask, always willing to help
Mal