With a sim, it all depends on how you set the sim up for your chosen heli, ie if we look at phoenix, there is a vast array of settings that can be changed just as in real life with a programmable Tx.
One of the easiest things to try first is to change the sim speed, by slowing it down to say 80% things will be a bit easier, then change the ground effect to 100% as in real life, then you can add the expo to your controls which will smooth things out.
As for model selection, leave the so called trainers alone for the time being, choose the largest heli you have available in your menu, as with fixed wing in general, the larger the model the more stable it tends to be.
As you get more proficient you can start to reduce tha amount of expo you are using, change to a smaller model and start to increase the sim speed.
Sims if set up correctly are a great tool for training, especially heli's, as with a real model, any sort of crash or hard landing will cost loads in repair bills, in fact my first hard landing with a belt cp 450 cost over £30 in spares required to get it flying again.
Tony