Please forgive me if I seem to disagree with anybody about play styles progression and forgive my foolish noob self in my early games.
But what do you want to get out of playing the game ?
Some people are happy just to stay around the tier III to V range and never progress up the tiers. Do you want a specific tank ? For me the only thing I wanted to do when I first started was to get that TIGER 1. I did not care about win rates or kills but only the experience points and silver that allowed me to progress as fast as possible to that goal. Played the game around 18 hours per day. Then I got it and found I was losing all the time. But is was a great tank in WWII stupid game is not working right. .....
Pause use for reflection on what I was doing yep, I was that bad of a noob.
Prior to the release of 3.8 what I think tended to happen was that the more experienced players tended to group into the higher tiers with tier 8 - 10 being the main places to find them. In the past the level of silver you got for fighting in a tier 10 game did not cover the costs of the fight in repairs and ammo unless you were very good. So what a lot of players did was to buy a good credit earning tank a tier 8 and use that to finance the tier 10 battles. The IS6 was the favoured premium for this.
Because of this the tiers 8 -10 I found were the hardest.
Now with 3.8 things are changing a bit, most of the experienced players are picking a few favourite tanks and fully equipping these. If you have just gone up a tier and run into one of these opponents in a near stock tank you are in trouble.
Occasionally now after 3.8 you get more seal clubbing, which is a experienced player dropping down into the lower tiers 2-5 using a heavily equipped fully crew skilled tank to get easy kills against new opponents. Often in a premium tank. Partly because of the way that the spare parts are dropping and it is far easier and quicker to fully equip a low level tanks rather than the 21 days it takes for a tier 10.
Sorry must stop pontificating and straying off topic.
You seem to have the right idea by gaining skills at a lower level and I agree with the purchase of the 75% crew skills if you are planing on keeping the tank for any length of time. However if you are just racing up the tech tree I would not bother with it below tier 5 by the time you have the experience points required to jump to the next tier only takes a few games and not worth the expenditure. I would also not pay the gold required to have a 100% crew skill on any tank at any tier.
Remember that when you do go up a tier that you will generally be facing much better tanks as they are likely to be better equipped and crewed than your own tank.
You will also have to play the tier 4 tanks at tier 3 you will be fighting up against some tough opponents the Matilda can be a really nasty as it is so heavily armoured when you are in a tier 3. Same goes for the Hetzer. Depending on what you chose I suggest that you take some premium ammo, bought for silver, do not pay gold, to have for these opponents otherwise you have to aim for weak spots and try to get round the back.
But if you like playing at tier 2 you can just stay there. We do not have a timetable in the game that says you must progress to tier 10 after X amount of games. If you want to progress and by your post I assume you do that's fine as well. Just so long as you are enjoying the game.
Good luck and shoot straight.