This all good advice, but you can also do it the way I did...

Buy at least a 5000 watt, gasoline powered generator light enough you can move it around by yourself. Done.

A fancier generator will have more features, all of which are the nice to have category. A Honda engine will run more quietly (so I'm told, I only have the one generator, so I don't know). I plan to run mine outside on the patio, shut it down, wait for it to cool down, then wheel it back in the garage (theft).

If you're pressed for time, especially, any generator is better than no generator. The generator you can afford is better than the one you're saving up for, etc.

Also consider buying an inverter. You can run small electrical stuff without having to set the generator up.