I would find someone in your area that you know that reloads and pick their brain. I have found it to be a very good resource and has kept me from making stupid rookie mistakes. Some of these mistakes can prove fatal.
I also started reloading for 7 mag a few years ago and have progressed into other calibers. If you are seriously going to start, stick to one caliber and get the steps firmly in grasp before moving to others.
I would also stick with ONE reloading manual of either the powder or bullet manufacturer you have chosen to use. It may be difficult to find some powders right now due to high demand and low inventories. Be patient.
For powders I use H1000, RL22 and have tried IMR4831. My gun likes the RL22 the best with mid weight bullets. Every gun will be different and may or may not like a particular load. Depending on availability you might look at Retumbo, H4350, RL25. The manufacturers post load data on their websites and give some good starting points. Be careful on using their max data, it may not be safe in your gun.