You should definitely get the red rifle as a starter gun, or lr pulsar which is decent for noobs. But from what I remember, it's impossible to do missions with only an er Beamer, maybe that was just me. Also, when you start getting a lot of money, start buying miner robots so you can get a lot of minerals to sell. +go around in a cycle for alien ships which can give u 100g each if u destroy them and they drop graaliums which u can sell too