Look up by shape
Find a kanji you cannot read by how its shape divides and how many strokes each part has. Start by choosing how the whole character divides.
Split the character into two parts. Choose "Left and right" if it divides side by side, "Top and bottom" if it divides horizontally, and "Enclosure" if one part surrounds the other. Anything else is "Other".
This grouping follows the SKIP system recorded in KANJIDIC2. People sometimes see a shape differently, so if you cannot find your kanji, try the neighbouring stroke counts as well.