Hi Leo,
My advice for when you are just starting out - keep it, simple, Keep it 1/35, keep it Tamiya!
Remember, 1/35 is a LOT bigger than the diddy small scale stuff you are doing now (you did a great job of that by the way - I'm terrible at small scale)!
I'd recommend you looked at a Tamiya Panzer III, a Tamiya StuG III Ausf B (I've got the StuG III Ausf B myself which I'm starting tomorrow) or you could go Allied and look at the Pershing or Cromwell maybe?
Remember, the bulk of the Allied tanks had 'live' tracks so their tracks didn't 'sag' like German tanks and one piece vinyl tracks, painted and weathered properly, do the the job just great as they are nice and taught.
If you got the StuG or Panzer III your tracks would need to 'sag' in between the return rollers at the top - this is where aftermarket tracks like Friuls come in handy as they look perfect. You can also also use the link and length tracks supplied with the kit but you won't get much sag with these. You need indy track links like Friuls or Magic Tracks supplied with Dragon kits which are also indy links and you can make them sag perfectly.
Personally, I find that Friuls are just awesome and look brilliant. They are metal (lead/white metal) and heavy so have a nice natural sag to them. The only downside is they aren't cheap - probably about the same price as a good 1/35 Tamiya kit so I only use them occassionally. You can also get Modelkasten tracks which wbill on here loves and he makes them look great. They are plastic but build up in a similar fashion to Friuls so they can be moved around and positioned. Get the sag in the right place and fix with a little cement. These are obviously a fair bit cheaper being made from plastic.
Best of luck,
ATVB
Ben 