People say progress is hard but it's actually easy. Don't work out the same muscle group within about two days. Easy way of dividing them is pull exercises one day (rows, pull downs etc, biceps...); push exercises (bench press, shoulder press, triceps); and a leg day... so all muscle groups in three days, or six days (×2) and then a rest day.
Easiest way I've found of progressing is first work out what weight you can do three sets of 8 on... I.e. 8 arm curls followed by 30 seconds of rest, another 8, then 30s, and then another 8...
If you can do that, increase the weight by a few kg the next time you work out until you fail to do a complete set (i.e. 8, 8, 5...). At this point, halve the weight and lift until you can't lift any more, halve again and keep going until you're basically at 0.
Record what you manage, and you'll find you will gradually improve.
I.e. 20 kg x8 (30s rest), 20 kg x 8 (30s rest)... third set you only manage 20 kg 3 x 8 so you drop to 10 kg until you can't lift it anymore, then drop to 5 kg until you can't lift anymore. The next time you'll find you can do 8, 8, 5... and then 8, 8, 8... at which point I'd give it another week on that weight and then increase it the following week.