First off, my jenner-D and jenner-K are two of my favorite mechs.
To be clear on a few things, I'm going to state ahead of time that:
1. My ping rarely goes higher than 100, or 130-150 on a really bad day.
2. I've never played any mechwarrior games before this, save for one game on the original Xbox that belonged to one of my friends, ~5 or 6 years ago. I didn't like that game. I love this one.
3. I have practiced with my jenners a lot, and I have the best upgrades I've found on them.
4. I'm in a clan, but I've only been with them for a few weeks, and only been playing with them for the past week or so.
5. DO. NOT. GET. FERRO. FIBROUS. ARMOR. Seriously -- it doubles the cost of armor per ton, and it gets you way less tonnage/critical slot used than endo-steel does. Even on lights, which are some of the only mechs which can fit all 4 upgrades. (double heatsinks, endo-steel, ferro-fibrous, and artemis.)
6. This is just the recommendation by one player. Don't assume I'm right, and what I've picked is what you will love, but don't assume I'm wrong either. Ask around, and read the threads. Even better would be if you joined a clan -- you only need maybe $20 for a good headset with a microphone attached, and teamspeak is free.
Okay, on to business:
For a new player, I have two recommended starting mechs:
Either, the Jenner-D or the Hunchback-4P.
Jenner-D:
NOTE: THIS MECH IS BEST IF YOU HAVE A VERY LOW PING. Ideally, less than 100 constantly, or at least 90% of the time.
The Jenner-D has two missile hardpoints in the center torso, and has 2 energy hardpoints in each arm.
The two CT missile hardpoints are best filled with two Streak SRM 2 launchers when you are a new player, because they home in on their targets. They don't hit 100% of the time, but they hit much more often than dumb-fire SRMs do.
The two energy hardpoints in each arm are best filled with two small lasers (regular, not pulse), unless you have a large engine AND double heatsinks, in which case you can use medium lasers.
The best engine I've found to use in a jenner (all jenners) is the XL 300 engine. Yes, it costs more than the jenner does itself, but with that engine, you are moving at nearly 140kph. Once you get the elite pilot skill 'Speed Tweak', you are moving at nearly 150kph. You will be the fastest mech on the field. Use this to your advantage. Dodge, weave, hide behind cover, anything to make it harder to damage you and take you out. Avoid mechs which also have Streak SRMs, because those will hit you unless you have cover everywhere.
This build, when it has small lasers, is fairly low damage, but very easy to manage heat if you use weapon groups correctly. (For me, I group the weapons on the right arm to weapon group 2, the weapons on the left arm to weapon group 1, and then chain-fire each weapon group. I then make weapon group 3 all of the lasers without chain-fire. Weapon group 4 is the Streak SRMs on chain-fire, and weapon group 5 is the Streak SRMs without chain-fire.)
Once you have enough CBills, get double-heatsinks, endo-steel, and the XL 300 engine. The XL 300 will set you back nearly 5 million cbills, (I think), but it is worth it in the long run. You do not need more than 1 XL 300 engine for your mechs -- just remove it from one mech and add it to whatever one you want to pilot next.
Hunchback-4P:
NOTE: THIS MECH IS A 100% ENERGY BUILD. The only ammo that should ever be on it is AMS ammo. This mech will have extremely low repair bills if piloted correctly, and, like the jenner-F (which is also a pure-energy mech), will have almost no ammo cost whatsoever.
The Hunchback-4P has 1 energy hardpoint in each arm, 1 energy hardpoint in the head, and 6 energy hardpoints in the right torso. Unless you have double-heatsinks and endo-steel, don't fill this with medium lasers. Go for small lasers instead, a 260 standard engine, (which will let you move at 84kph without Speed Tweak), and make sure that you have as many standard heatsinks as you can carry. You'll need them. Don't engage LRM boats unless you can get right in their face without them noticing you. You have no damage at all beyond 180M (your AMS has more range than your primary weapons do), but at 90M or below, you have a fast-firing, quick-cooling, 27-damage alpha strike. The first pilot skills you should get are Cooldown and Heat Management. (They are the two basic skills in the upper left and upper right corners, respectively, of the pilot skills screen for the mech.)
Once you have double-heatsinks, and endo-steel, you are ready for using Medium Lasers instead of Small Lasers. Now you can do full damage at up to 270M, and do some damage out to 540M. Beyond 540M, you do nothing. Now, however, you need to manage your heat a bit more carefully, because medium lasers heat up more than small lasers do. In exchange for that, however, your previous alpha strike damage/range of 27/90 becomes a much more appreciable ratio of 45/270. Translation -- you target the back of an atlas, and it will fall in, usually, no more than 4 alphas. You're still moving at 84kph, and that's fast for a mech with an alpha of nearly 50 damage. You also are fairly heavily armored.
This mech is great for 'farming' cbills. I don't mean cheap-***, d-bag lame, AFK or suicidal farming, I mean "contribute to the team like a BAMF" farming. You'll get fairly good damage, and, as you increase in skill, you'll get better and better at taking people out quickly.
For reference, this is the mech I used in closed beta before everything got wiped for open beta. I still prefer my jenner over it, if only because at 150kph I can pilot circles around most opponents, and that's
without the jumpjets on my mech. This mech will help you a great deal, and it works far better than ammo-heavy mechs, even if you don't use auto-rearm.
You should still avoid ferro-fiberous like the plague though. It makes farming so much worse in this mech.
However, don't take my word as being 100% right. I also happen to be a fairly good atlas pilot, but that is
not a beginner mech. And with the cheapest being 9M, it shouldn't be your first mech either.
Don't worry guys, you'll get there.