Just a quick heads up: in case you didn't know, the D.W. 2 (now known as the Death Wagen) has gotten the top 7,5 cm L/43 gun from the Pz IV D, and is now perhaps the best low tier vehicle to learn how to do the Heavy in - especially the German Heavy.
A lot of experienced players already liked the Death Wagen with the 5 cm, but I never really felt it was a proper Heavy tank. Now it is, the L/43 is a very capable weapon with better Alpha damage and it is more representative of the higher tier Heavys.
Skills to learn in the D.W. 2 are side scraping, angling, wiggling and hull down. Learning to bounce shots is one of the most useful skills in the game. Otherwise, pretty much the same deal as the Pz IV D - learn to take on higher tier opponents and prey on their weaknesses. KV-1s, Matildas, Hetzers, AT-2s and T-40s all have their higher tier counterparts, and if you can take them on in the D.W. 2, you'll be well on your way to being more successful in higher tiers.
A word of warning: some people say the Death Wagen is now overpowered. It is not. What it is is a very balanced vehicle that experienced players will immediately recognise as one that can perform well in. Don't let this talk of OP-ness give you a false sense of security, you still need to drive it well to make it work. A reasonably good player in a D.W. 2 can easily take out two less experienced players in D.W. 2s on the red team, for reasons stated above; they will keep their head down, angle, sidescrape and peek-a-boom, and they won't get frustrated and leave cover to let you get a shot in.
By the same token; don't let other D.W. 2s scare you. There are a lot of clueless players driving the D.W. 2 on their way to the Tiger I, and since the Tiger is one of the most notorious and well known tanks in history, that's not going to change. If you stick with it, you'll go through them like gas through silk underwear. And if you do happen upon a super-unicum player in a D.W. 2 and get slaughtered, don't feel bad. Just say "well played" in chat and stay to watch what they're doing, still one of the best ways to learn. Or why not ask them to platoon a few games and show you how it's done?
Hope you have enjoyed this short presentation of the "Death Wagen", the "baby E 75" or the ""Tier IV Terror", whatever you want to call it. I'll leave you with a final point on ammo selection. Carry a few APCR rounds (don't pay gold for them, pay credits!) for extra penetration, but try not to use them. Carry mostly regular AP, and then some HE shells as needed. As you may know, HE rounds had their penetration nerfed a few updates ago, but that does not make them useless. Do yourself a favor and download the Armour Inspector app, make sure settings are for Blitz (not PC), choose the 7,5 L/43 gun from the D.W. 2 as the gun firing, and set ammo to HE. Then go through all tier III, IV and V vehicles as targets. Some, like the Matilda, you won't be able to penetrate, but a lot of lower tier tanks can be reliably penned from the sides and rear with HE, some even from the front!
Armed with this knowledge, when in game, press the ammo selector button and let it stay open so you can change ammo in a flash. When you do, press twice so the tab is always open, that way you can change back quickly if needed. A few well placed HE shots will maximise your damage; you'll do 200 plus instead of 160, and in lower tiers this can make a huge difference. You do, however, run the risk of making less damage if your aim is a bit off.
This technique is pretty advanced, and as a new player you might want to skip it. It is a useful skill to learn, lots of players fire the odd HE round even in higher tier games, but do not let it interfere with your situational awareness. Being aware of the terrain and what's happening around you is still the most important thing.
Good luck, carry harder, and stay safe on the battlefield!