I think the main thing, as has been mentioned, is to upgrade your bottle to some form of fibre wrapped one.
48ci or a 68 are good, and all depends on how much preference you put on weight of setup, and the length of your arms essentially.
Most will get on with a 68 (or 1.1) but others like the smaller 48's. I myself can use a 'standard size' 1.1 (some can vary in shape) but it's not my favourite. As such I changed to a 48 (0.8) fibre wrapped and absolutely loved it - though, again there are issues with less air capacity. I've just bought a 1.1 guerilla with a myth reg (small and stubby regulators to reduce the length of your bottle to nearly that of a 0.7) and it's great, all the pros of a small bottle with the capacity of a 1.1.
Check the Lips / BZ / any other pb shop websites to browse the general bottles being offered.
You're not going to see any serious tournament / speedball / whatever you want to call it player using a steely.
Don't get me wrong, for the price they're great and an excellent way to get younger or newer players to afford their initial kit.
The problem is the weight, the shape, and the limitation of 3k. As most will say however, at many sites you'll struggle to find a >3k fill, but you'll be kicking yourself if you do find one. Also they're heavy buggers and still only 48ci / 0.7: not much air to be had.
This is all money dependent I know, but it'd be my first port of call. Upgrading bits on your marker before upgrading a steely is almost like having a house and buying new upholstery for the sofas before sorting out the electrics or water.
Just keep checking the classifieds as they can come up for as low as £60 dependent on amount of test.
- Feel free to poke holes in this if anyone disagrees