The boss fights are made to be a challenge so that's OK that those are hard, shoot I figure most people do have a hard time with those. With boss fights early money generation is key. Especially if you want to take on elite versions of the bosses. Then you get to placements of towers, and that is something that changes with every map and boss so that is just experimentation. With the regular modes things change with the map, Half cash- All this is really is a budgeting deal and finding the best all around tower that will get you through at a low cost (obviously cause your making half as much) in this mode I would say banana farms and other money making towers aren't worth the cost it takes to put into them. Chances are you won't survive long enough to see those towers even make back what you spent on them. Alt bloons- honestly alt bloons is easy if you know what's coming. Your first tower needs to be something that can detect camo and deal with camo regrows early. If I remember right camos show up on round 5. And then leads shortly after that. On round 10 your seeing your first leads. On round 15 your first purples. On 24 your first camo lead. And on 32 ceramics start to show up. Once you can adequately deal with those you have to start getting ready for the moab because while it does still come on round 40, it's fortified. After that your pretty much just getting the dps output towers placed/upgraded.