'HOW TO EASILY GET THE 'LOVABLE' ACHIEVEMENT IN FALLOUT 4'
The easiest way to obtain this achievement would probably be by obtaining 'Cait' (who can be found inside of the 'Combat Zone') and exploring the wasteland with no clothing on. Keep in mind, you are still able to use armour, you just aren't allowed to have clothing equipped underneath (e.g., 'Vault Jumpsuit', 'Marine Wetsuit', 'Minuteman Outfit', 'Synth Uniform').
Other ways to increase Cait's affinity include:
• Healing 'Dogmeat'
• Lockpicking
• Being selfish/violent
She also likes it when you drink alcohol/use chems, though it's good to note that she reacts negatively to both of these things after you complete her companion quest 'Benign Intervention'.