electrical gremlins

first off thank you so much for your help its really been a lifesaver as electrical is the one thing i truely struggle with, and i really appreciate the help, anyways, fuseable link is still good when i went to plug my meter into the bulkhead connector i noticed my headlights flicker so i just kinda pushed it in tighter and turned the key and bam! i have power! so glad to have found the problem so now i can deal with it! so what can i do to prevent this from happening again?