So, start with quantity and learn to appreciate good stamp design, town cancellations, color varieties, perforated initials, and the other attributes and differences that make stamps interesting. Before you spend serious money, learn as much as you can about how condition offsets the price of individual better stamps. Don't be a philatelic snob. Don't belittle others' interests. Collect what interests you, not what snobs tell you that real philatelists collect.
Stamp collecting is a disease, and it can become terminal.
Don't let it. Remember that your family comes first. The computer is a tool, not an end in itself. Use it to make pages, inventories, exhibit pages if that is enjoyable and practical, but remember the object is to enjoy stamps, not to be a slave to a machine. Visit dealer bourses and stamp exhibitions whenever you can.