Well, I'm not a beast, I wont be one since my net sux, but hey I get kills more than other people =)
So here's my loose change for you guys.
I use lightning, it doesn't take much practice to use and it gives you free kills.
~Free kills? Yes, if a guy does a 1x1 tower, this kills him. An over head cannon? No worries, look for the shadow and blow it up.
~It's pretty handy at times, it's better than chasing them with a 1x1 tower and getting blown to bits since you're busy building a tower while he's already placed a tnt and jumped off.
~These may not work though in maps such as dark passage and evil as they already have an indestructible roof.
~It costs 12 points and not really a profit grabber, but there is the good laugh in each kill with lightning; pausing for a few moments watching at this sitting(well actually hopping) duck trying to fly and zap... XD and comes the joy of him DOING IT AGAIN, lol
Also, I learned (FROM PRACTICE) rockets.
~Do not aim rockets at the players themselves, aim it at a block it would hit NEAR a player or at a block NEAR to where a player is headed as a player can dodge it but the block wont. It costs a pretty penny with 15 points but I've gotten double and triple kills with these.
Do not purchase airstrikes, nukes or cannons YET. They will not get you profit on most occasions.
~Airstrike, cost 150, best time to use : mini map with a full server or with a high kill streak. I only use airstike for fun, watching the chaos as it happens. You need at most 15 kills from it for it to pay for itself.
~Nuke, cost 1000, do not buy this at all if you're starting. I never bought a nuke before because 1000 points is 200 pistols and 200 pistols gets more kills than 1 nuke. But really, you'd want to upgrade your weapons than buy a nuke. A for-fun-only weapon. I dont know how many you need to kill to neutralize the cost of this since you get more points per consecutive kills, and I'm not counting that high.
~Cannon, cost 400, infinite ammo; I have never bought one on purpose, I bought 20 cannons by accident but I instantly sold them. You need to net at most 40 kills to pay the cost of placing one, but you'll need to do it while dealing with people trying to kill you and teammates that would be using it, you cant hog it.
C4s, my happiness
~So I upgraded my C4 with radius and got this :
http://i269.photobucket.com/albums/jj80/angelnepo/woot.jpg
~I placed it right beside a cannon where, lo and behold, people are drooling over the cannon. So yeah, C4 placement very crucial, whether it be on a cannon, a narrow area, a control point during king of the hill or in front of a flag during capture the flag.
So the weapons that I use are as follows,
TNT
Pistol
Rocket
C4
Lightning
Most importantly, save points for upgrades... I mean, uh, having fun is the most important thing!