DO'S AND DON'TS
1) DO have at least 1 ally, they can help a lot.
2) DON'T tell people your going to raid them, that gives them time to prepare,
3) DO attack at night time, higher chance if they do see you they may think it is a mob.
4) DO try to get a spy in their faction.
5) DON'T raid allies, no good will come of it, and you will get a bad name for being an ally.
6) DO enchant high level items, with 1.3 enchanting is MUCH easier now.
7) DO use as many beneficial potions as possible.
8) DO bring harmful splash potions, but be careful with aiming, i usually toss those 1st then fight them and don't toss anymore.
9) DO scout the area for a while before attacking.
10) DO bring a good amount of tnt after you scout so you don't lose it the 1st time you come and may die.
11) DO wait for night and lure creepers in if low on tnt
12) DON'T tell anyone outside your own faction you will/did raid someone recently, you don't want vengeance knocking at your door.
13) DO bring ender pearls they work magic when raiding.
14) DO bring a bucket of lava and 1 for water, use this to make cobblestone over a 1 layer water base. Then blast inside.
15) DO utilize glitches to get inside of bases, careful though sometimes admins see that in their chat making it look like your hacking, and may ban you.
16) DON'T forget to bring a decent amount of food.
17) DO bring a piston, on some servers you can make a bridge on their land using the pistons pushing power.
18) DON'T come with stuff you wouldn't want to lose, like diamonds, emeralds, enchanted tools.
19) DO know how to build at least a basic cannon (i made a cannon designs and concepts downloadable world check it out if you aren't sure how to make a cannon)
20) DON'T spam shoot tnt int a base after yoy blew a hole in to get inside, there may be chest behind that wall u made a hole in, and any extra tnt will blow up the items in those chests making the trip a waste of time and resources.

If enough people like this(favorite,Diamond,Comment/view) and my "how to not get raided" and "How to become feared" posts then i will add a lot more tipsXD