All digital components will require local bypass capacitors to smooth out power spikes. To compute the size of the local bypass cap, use this formula: C = I/[delta(V)/delta(T)], where I is the current used by the component, delta(V) is the maximum voltage deviation allowed for the chip, and delta(T) is the switching time of components in the chip. For example, if a 5V part uses 100mA, can tolerate a voltage drop down to 4.5V, and has a switching time of 5ns, then C = 100mA/(0.5V / 5ns) = 1nF. It is ok to pick values "close by", such as 4.7nF. However, make sure the caps are low ESR.
When you try to place bypass caps on your schematic, you'll notice that most symbols don't have power and ground leads. You can just use the VCC and GND symbols from the library to connect your bypass capacitors. They may appear anywhere on your schematic. Please see the schematics for ideas.

If you have unused inputs on any parts, connect them to power or ground as appropriate. Don't leave them floating.

If you build custom symbols for new parts, make sure to include all pins, not just the ones you are using.

If you build custom symbols, label each pin with its name. See examples.

Include the name of each subnet coming out of a bus. See examples.

Use connect-by-name for long connections that would be ugly if drawn out.

Include a fuse in your power supply design. See examples.

For testing purposes, all of your power supplies must be "isolatable" on both the input and output sides. Make sure to include jumpers or zero-ohm resistors so you can disconnect them from their inputs and outputs for testing.