I'd go with 4 or 5 x T1 to start with and then 3 or 4 of T2 and T3 - however if you aren't buying expansions and progressing at a normal rate then you may have to sell something later on as the infrastructure demands increase overtime.
I'd suggest going to the wiki to see exactly how much things will cost.
Its very tempting at the beginning to load your city with T1 (marble, steel, planks) but you still need room for the other tiers as you research them on the tree.
The other thing is to only build your boosted factories, and trade for the non-boosted, you won't see such a big difference in production at the beginning but you can expect a 700% boost by collecting relics of your boosted goods type plus extra by placing/upgrading the Mountain Halls Ancient Wonder.
