This is my favorite tip: Send each other cute, funny, or sexy love notes. Not emails—real mail, people! You don't have to send pages and pages of love letters—just something short and sweet. Etsy is a great place to find creative cards. My BF and I each send each other one a week.
Since I am in a long distance relationship, there's never a day I lay in bed wishing my love was laying next to me. Some nights I may just call him, just to hear his voice so I can sleep. Him being so understanding, he'll never let my call go unanswered because we both know that we need each other. Knowing that the love between us is mutual is the only factor keeping me sane from these days without him.