Be prepared to invest in more equipment. Think about the time periods you have available for operating. EME, for example, sometimes requires operating late at night. Consider the operating environment you prefer. SSTV frequencies are often more crowded than RTTY frequencies.
Packet radio is similar to the Internet.
Set up the equipment you've chosen for your new mode. Read manuals thoroughly. Listen on the appropriate frequency. Do not transmit until you understand the unwritten protocol and agreements. Operators using different emissions sometimes seem reluctant to accept newcomers.