Read all the recent build threads and get to some events to talk to people. See robots up close and make a note in your phone of what people use. It's what most of us did when getting into it. Obv people will help you but there are a huge range of abilities, so some will say draw it in CAD and get it cut, others will make it all themselves. It sounds nasty but there is a level you need to be at to get started (volts/amps, wattages, basic RC stuff, basic drilling and cutting etc.). There's a ton of interest in this at the min with it coming back on the telly, and it takes a lot of cash to go from enthusiast to competitor. Build a pusher, read the threads, get to some events, ask a team if u can tag along etc. Get into it first before spending cash and hurting yourself with pneumatics.