A few of mine I will share:
1) Battle on the map (NOT PvP battles):
Always attack, then retreat, then actually attack. You will not only get a good look at the terrain (useful for rangers, etc), but will see the movements of AI troops, surrender before any siege, etc. gets an attack in. You will get the same terrain and movements on the next attack. Since long range troops act last, this shouldn't ever be a problem. Repeat if necessary to know your defender. Understand the game mechanics and use troops that will exploit this terrain and unit movement.
Not so much use for your neighbors, heh, but I would also recommend keeping an eye/record with what they defend with, most players never change their defense until they advance--you should change yours, keep them guessing.
2) Acquiring BPs from fp donation:
Befriend players with the building you're targeting and having no luck with p/m-ing, they're not hard to find. Next time your fp meter is full, throw one point each on 10 different players buildings (of the same type). Check your great buildings tab in the town hall when you check in and keep an eye out for the best deals as buildings start nearing the next level. You should always keep a forge point package(s) for just such an occasion. Also I suggest saving diamonds acquired within the game for that 9th elusive bp on a GB you're gunning for. Best bang for your diamond buck in the game.
3) Real Estate
You can always stick a military building between buildings (disconnected) for temporary space, provided its a building you need-hence don't want to rebuild-but don't need to build new units of the type for the time being. You always want your culture, gold, and supply buildings connected, but if you don't need the troops, it doesn't really effect the military buildings, as you can still attack with what you have.
You should also strive for ZERO decorations, as in having no space to put any, and minimize your roads. Decorations give an option to the visitor to p/m something you don't want him or her to polish when there's better options for yourself. Besides, when broken down, arguably the only real strategy within the game is puzzling your city together for maximum efficiency. Wherever there's a road or decoration that's unnecessary, that's space that could of granted you something else.