Yes, primarily salt can dry out the meat.
If you want to start trying/using injections (I do and have bee largely pleased with the results), I suggest that you start with simple ingredients, and in small amounts.
For example, most competitors start out with their own version of the highly published Chris Lilly's injection. I happen to find his injection unbelievably salty. Most competitors (on pork mind you) use apple juice, a little worchestershire sauce, and a little of their rub (not so much that it clogs their injector) and inject about an hour, give or take, before they put the meat on the smoker.
The reason I say "competitors" use this, is because they know to not having something too strong one way or another so as to offend anyone.
There are all types of injections you can try. Some like the vinegar based, others the creole butter based, some coke or dr. pepper based, etc.