I wish there was an idiot's guide to weight training and the machines. I am trying to follow along on some apps but really struggle to understand which machines to use and how to progress on weight training. I see nothing that helps you figure out how to do this on your own. If i could afford a trainer I'd get one but money is tight and I also don't see myself dropping $150 a session any time soon.
With progression, take it super steady at first. Your muscles will ache (DOMS) for a day or two after sessions. But after 2-3 weeks you should start noticing things feeling more comfortable and thats when you can start pushing yourself more and start seeing the numbers go up (weight and/or number of reps). But be patient with your body the first few weeks!
A lot of gyms have duty staff whos job it is to make sure people are safe which includes showing how to use the machines properly. This should be included in membership - not talking getting a program from them, but being properly inducted and shown how to use things safely. Covers their own backs from folk getting injured. It might be they only work certain times of day/you need an appt, but worth asking!
One key thing I think with strength training is keeping good form. It is better to go for an easier weight/option and keep things full range of motion than try heavier but end up using the wrong muscles or a smaller range of movement.
Try not to move your whole body, squeeze your core/tummy tight (as if trying to stop yourself to pee and hold tour belly in) to stabilise yourself and only move the muscle(s) that are being trained and keep it as steady and controlled as possible.
All muscles are strongest in the middle of their range of motion, the best benefits come from challenging them to work their full range of motion. E.g. bicep curls (arms). Yes, you can lift a lot more if you keep your elbow bent around 90 degrees and do small movements in the middle of the range of motion, but this is not training the full muscle. You want to keep your elbow locked by your side and fully straighten your arm then bring it all the way right upto your shoulder. And without arching your back to get momentum (thats using/training back muscles to lift, not bicep muscles and also has higher risk of injury due to fast/jerk movements).