Oh , and remind yourself that you dont need to fear a fast , flat one being darted down the leg side for a stumping if you don't leave the crease until the ball has left the hand and is above the eyeline . Basically. ... don't premeditate.
Yes, agree with all of this. Wait until you have a feel for the bowler, and never just bat by numbers. When I'm ready to go a couple of steps out to a spinner, I premeditate in as much as I step out with the deliberate intent to defend. You don't have to dash forward, just take a couple of gentle half steps and defend off front or back foot as appropriate. Show the bowler you're not concerned about his turn, by stepping forward with care you should be able to smother whatever comes.
Second step for me then is to fake stepping out a couple of times. Put the pressure on the bowler, if you fake when he is in his delivery stride, he may well panic and drag the ball short. It will often sit up for a pull or cut.
Finally, wait for the ball you really like, I prefer an off spinner who tends to pitch up. If you've got your eye in you'll pick the right one, and then be sure go all in. Plan to play hard off the front foot, and play it high if Mid-on / mid-off are up, or low if they are back. Of course then try to find the gaps.
I always use nets as the place to practice, but you need the bowlers to know what you are doing, and feed it. Don't just let then roll up and bung rocks at you. Don't waste net sessions, they are short and few in number. Make the most of the opportunity to tune your special shots. Otherwise, you try them in the middle for the first time and hey, now you are out.