E4 is a lot of fun in multiplayer, particularly because unlike single player, there's actual challenge. While your skill in single player will certainly help, there are a few things that are different, and knowing them will help you even more.
1. Keep your beat bonus up. If you ever have a beat bonus under 3.0x, cancel your chain as soon as possible. Your first one or two explosions shouldn't even hit anything; just explode immediately so you can get your beat bonus up quickly. Keep that beat any way you can, perhaps by tapping your foot or even moving your whole torso to the beat.
2. Get Quickens as soon as possible. If you're playing with normal Quicken, you'll want to grab them all in between explosions. When there are as many Quickens floating on the screen as it would take to get you to 20, cancel your explosion and get them. Meaning, if you have 16 and there are 4 on the screen, go get them immediately. If you're playing with extreme Quicken, keep in mind that the first Quicken you touch will increase the tempo from minimum to maximum.
3. It doesn't ultimately matter where you explode. Don't worry about getting in just the right spot. You won't be going for big chains until you're at max Quicken and 3.0 beat bonus, and at that point, most of your chain isn't even on the screen yet.
4. Watch the score carefully. You'll want to let 3.0 beat bonus chains go on as long as possible, unless you're about to die. If you're ever behind by more than 75, cancel immediately. If you wait any longer, your chain won't cash in quickly enough to cancel your opponent's attack, and you'll die. You can cancel as late as 80, but I do at 75 just to be safe.
And that's the extent of the strategy for this game. Keep your beat bonus up, get Quickens quickly, and cancel if you're about to die. If you keep these in mind, and are good at keeping the beat, you'll do very well in multiplayer.
