My recommendation is to go to any field with walk-ons/skirmish days. I've played Siege, it's great. I also play a variety of outdoor fields, including Storm the Beach near Peterborough, Rapidfire near Picton and others. Heading to Clarington Woods tomorrow, actually. Once you have a feel for the game, start researching some milsim events...it's a totally different type of game than skirmish days.
Once you get to a field, let players know it's your first time, or that you are a noob. In my experience, most players are willing to help noobs learn, and maybe let them hold their airsoft guns to get a feel for the different types of guns if you don't have one yet. We remember being new once, too. Just remember that you have one mouth and two ears for a reason...keep the attitude to a minimum, and you will have a great time.