Reselling something over and over again can be applied to your own products and/or services. Even businesses where every deal is its own special thing should find how to make them more similar to refine their process of selling the same thing over and over again.
Practice really is the only way to get good at it.
It's definitely safe to adjust pricing after launch, even for subscription products. The key is to grandfather users in at their current rate if you are raising prices, and to charge them less if you are lowering prices.
You can probably even do a direct A/B test on price if you want, although you have to be careful and considerate if you do so.
You could tweak the subscription in ways that don't really change your costs but allow you to price as separate offerings. Monthly vs. quarterly vs. annual. Data limits, bandwidth limits, different features active, different levels of support, etc.
Practice really is the only way to get good at it.