IF doing bench press without spotter try to use a smith machine or power lifting frame with adjustable stops. If doing free weight barbell bench it is advisable not to use collars to fix the weights on the bar, so if you do get into difficulty you can tilt the bar to one side and the weights will slide off!
For proper execution you should start with the bar on the stops so you just need to lift it a couple of inches to clear them, the bar should be lined up midway down the chest not up at neck level although some experimentation with the position will give a slightly different feel to the exercise but always think of safety and where the bar will end up if you do suddenly lose control , the same will apply to hand grip where a hand spacing on the bar which gives close to 90 degree angle at the elbow will be normal position but again different hand spacing’s will give a different feel to the exercise.
Do not use a false grip (wresting on palm with thumb on same side of bar as rest of the fingers) always keep the thumb wrapped round the bar and keep the wrist locked tight throughout do not let the wrist bend right back. Keeping feet flat on the floor bum and upper back should be in contact with the bench and a natural curvature of the lower back maintained throughout, the torso should be ‘locked’ in this position throughout. If you need to move your upper body about or lift your bum off the bench to get the weight up it is too heavy. Back off and reduce the weight slightly so you can maintain good form, it will save you from injury in the long term!
As you bring the bar down breath in and expand your chest stop the bar just short of your chest and drive it back up breathing out and feeling the contraction in your Pecs, you will feel your shoulders and triceps working hard too and working on those muscle groups will also help increase you bench press weights. At the end of a set always make sure the bar is resting firmly on the stops before letting go of it especially on smith machines where the hooks may not be fully over the pegs but can feel as if they are.
Disclaimer: This site is for entertainment only, please seek professional advice before trying any kind of new physical exercise.