Welcome aboard.Trust me, if you are only north of thirty, then you are not an old git. I'm 49, but I've treated life like Blackjack and stuck at 21; you are as old as what you do and how you feel (and as the woman you feel lol).
There are quite a few starter advice threads stickied on this forum, so I'd suggest looking at some of those, but the gist of it is, go and play a couple of games with hire equipment from a local site whilst you see what kind of gear others are using and discover what you think might suit your playing style (which you will develop). This may vary from site to site, since some sites are purely indoors CQB and other woodlands, whereas some combine the two.
Many sites use the kind of guns you might expect as hire guns, i.e. G36cs, M4/AR15/M16s, MP5s and AKs of various types. But whatever you end up with as a hire gun, you'll find that most airsofters are friendly enough to let you have a good nosey at their gear, and it is worth asking about, and holding a few weapons to see what fits you well, so turn up early and get chatting. For example, if you've never had an early variant M16 in your shoulder, you might be surprised as to the position of the buttplate and so you might like an AK47's stock position better.
Obviously something small and easily handled such as an MP5K or a Skorpion or an UZI is going to be a better choice in the tight confines of CQB, whereas out in the woodlands, full size rifles such as an AK74, an M16 or a SIG 556 or some such would be a wiser choice. This is the reason many people go for an M4, since you can get short versions with a collapsible stock that suit both situations. That and the fact that there are tons of airsoft M4s available and lots of fancy add ons and gizmos you can customise them with, way more is available for the M4 than any other airsoft weapon. This is also why many people on here will recommend the G&G Combat Machine M4, because it is a very good and relatively inexpensive weapon which will serve you well for a long time and suit many different combat styles. But, if you find yourself preferring Eastern Block stuff, then there are of course many AK47/74 variants with folding stocks that can be used for CQB and longer ranged engagements. If you prefer something else, many site use Jing Gong G36Cs as hire weapons, those are alright actually.
At some point you will probably want a pistol, as a back up sidearm, but to be fair, this can wait a while unless you are intending to go to a more CQBish site, in which case it might be a sensible purchase somewhat sooner. There are certainly lots of pistols to be had, and what you see with pistols is more variety in the propulsion they use, some are simple cock and fire spring powered affairs, some are electric semi-automatic, and some are gas blowback (GBB) semi-auto, using either green gas can refills or Co2 capsules. You should be aware however, that GBB pistols are affected by temperature in terms of performance, so if you are going to get a pistol, weigh things up carefully and do plenty of research. Look at it as a long term objective if the idea appeals, and just go for for an assault rifle of some kind in the interim.
Also, avoid the notion of being a sniper when starting out. Being a sniper is often expensive to get into and requires you to start customising weapons to get the best out of them, whereas a decent electric airsoft assault rifle is pretty much good to go right out of the box, although on that subject, chuck away any BBs which come in the box your rifle arrives in, the chances are they'll be shite and can even damage your guns internals, always use decent polished ones.
Obviously if the notion of Milsims appeals to you, you might already have decided that either NATO or Eastern Bloc stuff is your preference, so that will have a bearing on what you should consider getting hold of. But some things you certainly could consider getting hold of sooner rather than later, would be protective gear.
Most sites insist that players under 18 must wear full face protection (and they will rent it to you), whereas over that age (as you are) they will only insist you wear eye protection. Whilst only wearing eye protection is appealing from a milsim point of view, you should be aware that it is fairly common for those who don't wear lower face protection, to end up getting teeth shot out, so I would recommend going for some kind of goggles
and some sort of lower face mesh as well. Note that perspex goggles are notorious for fogging up, so you might prefer mesh goggles, which are able to breathe. Don't go for something bulky either, since it will end up preventing you from getting your weapon up to your cheek to aim! Some knee and elbow pads help, they keep your knees dry when you kneel and stop stone floors hurting your knees too, and modern infantry soldiers wear them anyway, so they are milsim-ish. Likewise elbow pads, which also protect you from a BB hit in the elbow (which bloody hurts). On the subject of which, I'd also recommend a Keffiyah scarf (also known as an Arabic shemagh), since they protect you neck from hits (which also hurts, especially on the Adam's apple), these too are very milsim-ish as well as practical, in fact, the British army now issues these to troops going to desert theatres of operation, and the Yanks used to ban soldiers from wearing them, but have now relented and let them do so.
Obviously a helmet is not a bad idea too, although frankly, a baseball or forage cap will stop most BBs from hurting if they hit you head, so just use one of them whilst you suss out what you want. Thin leather gloves will stop you getting painful hits in the knuckles. A decent water bottle is a good idea, but get something small enough to be portable easily, i.e. a plastic water/coke bottle from a corner shop will do. Most people wear webbing equipment belts to carry spare mags and all their other crap, but don't worry about that too much when starting out, since most hire guns will have a high capacity magazine which shouldn't need reloading much, if at all, although it has to be said that webbing and equipment belts do stop BBs from getting you in the nipple (that bloody hurts!).
Ebay and Amazon are your friends for a lot of stuff, but if you want an easily navigable site which has a lot of the kind of stuff you might want to consider, then here's a useful one which is fairly cheap (although it is mostly NATO stuff). As a general rule, don't just look on one site, shop around:
http://www.tacticalgeartrade.co.uk/
Last but not least, be honest and call out your hits if you feel or hear them, and if in doubt, take the hit. Unlike paintball, airsoft relies on honesty for people to call their hits much of the time, and without that honesty, it is ruined.
