First of all, you should remove the screws of your shower head and check if there is something obstructive. Clean these screws by using a brush or just rub them under running water and reinstall them at their place.
You can also increase the pressure of water in your shower by removing the flow restrictive which is usually installed in the shower head. The flow restrictive always reduces the pressure of shower and if you want more pressure, you should remove the flow restrictive.
Almost all showers come with flow restrictive installed in shower heads. Removing it will create much more pressure than you want. So, you should try to purchase showers heads with less pressure because when you remove the restrictive of these showers, you will get a good pressure of water but it will not overflow.
A change in your schedule of taking bath can also increase the water pressure in your shower. If you take shower in non-peak hours like late night or early morning when no one in your family is using another washroom, will help in increasing the pressure of water in your shower.
Make sure you have checked all water tabs of your home and shut if you find any tab running. It will help in increasing the water pressure in your shower.
Do not forget to check leakage of water which is another reason that reduces the pressure. If you find any leakage of water, immediately fix it which will also help in increasing the pressure of water in shower.
Clean the screws of your shower head with regular intervals in order to keep the flow of water smooth and it will help in maintaining a good pressure of water in the shower.