[DGDobrev]

I would strongly suggest you start over and try to minimize your losses. Here's one way of doing that:

1. Scout all free resources (money, crystals, flags, chests) in Greenwort and the adjacent maps. Save VERY often and run away from the enemies or try to get them stuck somewhere and get past them.
2. After you have all the money you can get, go to the abandoned castle in velarion forest and do the skeleton quest and the treasure quest. It takes a few tries to do it without dying (the enemy usually catches up to you quickly in the small room with the treasure, so save before entering the painting portal in the throne room). If you manage to do this successfully, you will have like 50-60k (at least) in gold and 1-2 levels up (depending on the difficulty), which will net you some runesto advance in some skills, as well as some leadership, if you decide to start taking the upgrades from lvl 2.
3. There are a few more easy-to-do quests that do not involve fighting like some in the mage's school in Greenwort, the old chvakha quest (the one for the alchemist - you can evade the enemies along the way). Do them, if you can.
4. Now for the hard part. Recruit as many units as you can. Go to the horsemen's camp in Greenwort and save. Kill the enemies and save. Then kite the mages away from the camp, then go past them and recruit as many units as you can. There will be horsemen there (almost guaranteed) and Knights (rarely). Both make very good tanker units in the early game and will get you through every battle without any problems (magic shield on them, some heal and ranged units work on every difficulty without losses even versus better armies than your own). Same strat works on the turtle.

This will be enough to get you through the starting areas and up until the time to go to the freedom isles. Before you get there, kite the mages again and get everything in the camp. With a good tank and decent support units, the islands will be a breeze, even on impossible.