“Should i use a bar or a dumbbell?” 

This is something i hear quite a lot and I’m going to go through a few pros and cons to using both. I personally love the contraction i feel in my muscle when I’m using dumbbells, purely because it involves more muscle fibres to be recruited and other muscles having to work as stabilisers. For example when your performing the chest press exercise with a dumbbell your using a lot more of your core muscles to actually get the weight up, another thing is when your using dumbbells your actually isolating the muscle more than you would with a bar. On the other hand using a bar can great because the weight is distributed evenly therefore making it a little bit of an easier exercise to get the hang of. All that being said you weather you prefer using dumbbells or bars you need to make sure that you use BOTH. Spend a few weeks practising your technique using dumbbells then go on to the bar and then back to the dumbbells. Using one more than the other will result in an imbalance and your body will begin to get used to it and ultimately stop progressing.