Using 2N7000 with 3.3V signal
The 2N7000 is inappropriate for this application. At a 3.3V Vgs it will only conduct a few mA before the voltage across it may rise unacceptably. 

A more appropriate part for switching a small-ish motor might be the AOD424 which is guaranteed to have less than 5.7m\$\Omega\$ Rds(on) with 2.5V drive (at room temperature, it will be considerably more when hot). However, it's only rated at 20V so it can't be counted on to switch a 24V motor. 

The 30V-rated IRFR3708 has less than 30m\$\Omega\$ Rds(on) with 2.8V drive (more than 5x worse) and is a fair bit more expensive (around double).

Generally the higher the Vds voltage rating, the less likely you'll be able to find a suitable part that can be driven directly from 3.3V logic, so if you need to drive a relatively high voltage motor you'll want to use a gate drive circuit that gives you 5 or even 10V. 

Motors tend to draw quite a bit more current when starting, and that should be taken into account. A 1A motor may draw 10A or more when starting. They can also produce voltage if inertia or something else spins the shaft so your circuit should be designed to not be damaged by that. 

Also you should incorporate low voltage lockout (or suitable heat sinking) in your system level design so that it's not possible for the MOSFET to be destroyed if the system power is at some intermediate level that partially turns it on. Obviously that's much more likely if the power source is from batteries, but it's a good idea to consider even mains "brown-out" conditions to make your design bulletproof.