I don't think you could add a portico to a garrison colonial. The projection of the second storey would get in the way. Wouldn't look right, either, for a garrison colonial. But to help dress up your door & add more charm to your house, you could add wider, more decorative trim and maybe splurge for a larger, beautiful lamp. ETA: Oh good, I'm wrong :) A portico would be attached to the upper storey like in this picture. So go for it! It would dress up your house nicely.

Nice house and lot. Storm doors are practical to reduce heat exchange in really hot and/or cold weather -- would not remove it. Might consider removing that row of small shrubs immediately in front of the porch that is alongside the sidewalk in order to make your sidewalk more prominent and inviting, perhaps enhancing the sidewalk itself by outlining it.. Perhaps you could move those shrubs to the side or back boundary of the property.

I would stay away from dark colours for your front door. Because your door is slightly recessed and at the back of a covered porch, it's in the shadows. A dark colour will only make it look more shadowy. Because you have both cool and warm colours in your house, I would stay away from a colour entirely. My choice would be bright white. That will bring it out of the shadows. Add pots of flowers for your pops of colour. And maybe beef up the landscaping.

Thanks!!