Yeah I've had mine since halo 2 as well. I'm just glad that they kept the diamonds through all the games. I think to make mine bigger I enlarged it in photoshop. I also tweaked the color to be a brighter green (that matched my sig). I'm not sure if mod's can do larger avatars than members but send me a PM if you need help.
When I play Team Snipers I just run to the other base and assassinate everyone. Gets me a good KD ratio if I can get to the other base.
A team snipers game where I just went for assassinations. I couldn't find my best one but this was pretty good. For reference, a team snipers game where I tried to snipe. On topic. I don't even go for power weapons or good vehicles at the start of the game. I just end up throwing them in the water or walking out into a kill zone to piss off other people too often. Probably the biggest reason I hate paradiso is that half my team ends up camping in the tower waiting for the banshee to spawn so the game feels like team doubles on a giant map.
Steps 1). Get a Sniper 2). Go near a cliff 3). Shoot Team mates 4). make them go near you 5). Jump off cliff