Tip #1 - Try to not do your massages in a soft bed.
While the bed might be one of the most comfortable places in your home, this doesn't make it a good place to do your massages. Often times beds are too soft which is bad for a couple of reasons. First, it makes it difficult for the "massager" to be in a massage position that doesn't strain their body/back. Second, a surface that is too soft puts the massage receiver's spine in an uncomfortable position. And on top of that, a soft surface makes it difficult to apply the amount of pressure required for a good massage!
If you're looking to be an avid massager, a massage table works best! If you don't have one of those on hand, try and do leg massages on the floor, and back/shoulder massages on a chair. (Sit on the chair backwards with a pillow between your chest and the chair.) Of course, you may try these things and decide that you prefer the intimacy of giving massages in bed, or in some other position. That's OK! It's about finding a position that is comfortable and effective for BOTH people.
Tip #2 - How to add extra pressure.
If you're feeling like you just cant provide the pressure needed for a good massage, then the best thing to do is "reinforce" your strokes. Instead of massaging with both hands at the same time, switch to just one! Support that solo hand by grabbing your rist with your off-hand which will give you that extra stability and strength for more pressure.
Tip #3 - Use your bodyweight.
It's easy to make the mistake of applying all the pressure with just your fingers, hands, or arms. This still feels good for the person getting the massage, but is exhausting for the massager! Put yourself in a position where you can use your bodyweight to add pressure into the massage. For example, if you're giving a back massage, as the massager your entire body should be moving up and down the back with each massage stroke. This helps you keep up the pressure without killing your fingers, hands, and arms.