To get lower alcohol, you either reduce your grain bill for a given quantity of beer, or plan to mess up your mashing and destroy your efficiency.
The first option is definitely the better one!
The other thing with lower alcohol beers is that generally you mash at a higher temperature than you would for a standard beer. That means mashing in the region of 68 to 70ºC. I don't use unmalted grains in my low/mid alcohol brews.
One of my favourite house beers is a Mild. Here's the recipe from my last one. It's delicious drinking, with plenty of flavour, nice deep colour, and normal body. If you didn't know it, you'd never guess it's only about 3.4% ABV. I amazed our last house guest with it. One comment was how I got that much flavour in a mid range beer, when most if not all the commercial offerings tasted like nothing. I didn't go into specifics, just told him it's all down to the skill of the brewer!
MILD
Batch Size: 22.50 L
OG: 1.037 SG
FG: 1.011
Estimated IBU: 26.1 IBU
Brewhouse Efficiency: 80.00 %
Mash 60 min at 70ºC
Boil Time: 60 Minutes
3000.00 gm Pale Malt (2 Row) UK (5.9 EBC) Grain 83.33 %
250.00 gm Crystal Medium (145.0 EBC) Grain 6.94 %
200.00 gm Crystal Malt - 60L (Thomas Fawcett) (118.2Grain 5.56 %
100.00 gm Wheat Malt, Dark (Weyermann) (13.8 EBC) Grain 2.78 %
50.00 gm Carafa Special T2 (1150.0 EBC) Grain 1.39 %
23.00 gm First Gold '06 [7.90 %] (60 min) Hops 20.6 IBU
6.00 gm EKGoldings [4.80 %] (60 min) Hops 3.3 IBU
14.00 gm EK Goldings Plug [4.30 %] (10 min) Hops 2.3 IBU
1 Pkgs London ESB Ale (Wyeast Labs #1968) Starter