I used to have mushy pickles too, then got some good advice. Start with FRESH cucumbers. Use white vinegar and distilled water. The distilled water really made a difference. My recipe calls for equal amounts of vinegar and water. Also add 1/2 tsp alum in each quart. Process no longer than 5 min. or do not process at all.
For the no process method, you pour the boiling syrup over the cucs to 1/4 in. from top. Put on sterilized lid and tighten ring. Turn upside down on towel until cool. By this time the jars should be sealed. If a jar does not seal put in refrigerator. I know this is not recommended, but my mother did this all of her life and never had a bad jar. I just opened a jar of these that were made 2 years ago and they were excellent. There is so much vinegar that they will not spoil easily. Just make sure everything is very clean when you make them.