I built my base a long time ago, so I don’t remember the details, but as a general guide, I would recommend prioritizing your stronghold.
My recommendation is that you level up farms and mines to match your stronghold level, but to build your stronghold, you will need to increase your iron capacity (for the final level, you will need them all at lvl 18). So iron storage is important. For hero ascension, you will need to level up food storage. So these should be built up as well.
Now the big question is forges, training camps and houses. You want to build houses for at least 100 recruits. More than 120 or so is not an immediate necessity, so stop building houses at that point. Forges are used to make items to use up your extra resources. Make sure you can make arrows and minor hp potions.
Training camps: get these all to level 4 ASAP for low cost hero training. These then should eventually move to level 11 where you can keep them until season 2.
Now the biggest advantage of paying for this game is your heroes. If you do not pay, then you need to move towards training camp lvl 13 and then 20 urgently to unlock a chance at the best heroes. If you do pay and buy your heroes, then you can just stop at TC 11 until you build up your base (max farms, mines, watchtowers). Along the way, use TC 1 and 2 to provide heroes for feeding. Once that is done, you should build up one TC to 19. This will then allow you to finish a number of heroes quickly.