There are three elements that will make a big difference for you - new colors, new front door profile and an entry deck/trellis. For modern flair, I'd lose the white and build on your olive idea. On budget, start with colors, then add new deck, later door, then pergola trellis entry. Consider these options -

Right now the house is unbalanced because the foundation stone is lighter than the roof. Since you are drawn to the olive green (which would be great for trim and new wood elements), use a darker taupe brown masonry stain on this wainscot / foundation element, then go to a cool taupe in a mid-tone on the body of your home. Paint the trim around those windows and door where you now have white out to a mid-tone olive, and use a deep olive green on your shutters.

Instead of a bright primary for the front door, you can upgrade with wood stain or go mustard yellow (think brown mustard), or match the deeper green on the shutters. See crestview doors here's my pick for your house style http://www.crestviewdoors.com/order/crestview-doors-and-entry-systems/lafayette-a-door.html

Since you have the gable over the two windows to the right, I think you could build a. modern version of an open wood trellis with an off-center gable / peak nice and wide over a larger entry porch platform with stairs that ran the width of the platform down to grade. Off center gable concept http://www.google.com/imgres?q=off+center+gable&hl=en&tbo=d&biw=1600&bih=805&tbm=isch&tbnid=YcfNZb94n9SNDM:&imgrefurl=http://designbridgebeacon.wordpress.com/2011/02/25/&docid=vw4R2Oc3o5TrdM&imgurl=http://designbridgebeacon.files.wordpress.com/2011/02/off-center-gable-transverse.jpg&w=3015&h=2010&ei=VI4VUY65G9DiyAGT94GABQ&zoom=1&ved=1t:3588,r:0,s:0,i:81&iact=rc&dur=2189&sig=110993545148006135044&page=1&tbnh=172&tbnw=258&start=0&ndsp=27&tx=132&ty=74 gives even more modern look, with this off-center peak centered over front door nd the left side coming down long and low angle (isoceles). Here's a version of the stair / deck idea http://www.sunset.com/home/outdoor-living/ideas-for-deck-design-00400000061353/page19.html or http://www.sunset.com/home/outdoor-living/ideas-for-deck-design-00400000061353/page5.html that takes the stairs into additional space. Can you imagine corner stairs intersecting path near tree? Combine these ideas with an open gabled pergola over a new entry deck like so http://www.google.com/search?hl=en&site=imghp&tbm=isch&source=hp&biw=1600&bih=805&q=modern+pergola+designs+pictures&oq=modern+pergo&gs_l=img.1.3.0l4j0i24l6.1085.4515.0.7800.14.10.1.3.4.0.97.786.10.10.0...0.0...1ac.1.2.img.3e_CbNQ1teU#imgrc=5ee66_l7rd4KqM%3A%3BzrDabvMJt0RRkM%3Bhttp%253A%252F%252Fwww.spaced.com.au%252Fimages%252Fphotos%252Fspaced_103724382el1169699647%255B1%255D.jpg%3Bhttp%253A%252F%252Fwww.spaced.com.au%252Fpergolas-design-ideas%252F%3B800%3B600
This would add big modern flair, without intersecting existing house but you could add skylights in the last 1 or 2 rafter pairs against the house (or use inexpensive acrylic greenhouse panels like shown here) to give shelter at the entry.

I would start one post half way between the front door and the window to right and the other post not more than 12' to left (usual engineered span), just outside shutter on left window. Make the top of the gable peak about 18" higher than the existing gable on the roof over the other windows so this one is predominant.

Run the deck all the way to the outside of left support outside the window on the left hand side and to the shutter on the next window on the right hand side. Staining/painting this wood the olive green of the trim you place around the windows, and painting your entry deck the dark green of the shutters would be awesome, as wood leaving it all wood stained. Paint ornament now on gable out like shutters. Spray out gutters with oil rubbed bronze spray paint.

Hope these ideas inspire -