Can't remember where I got this from, but I thought it was really useful:
First and foremost, marry the person who is right in both your heart and your brain.
Look at things from their perspective.
Do something romantic on a random Tuesday.
Give compliments often.
Volunteer to do a chore that they usually do.
Say ‘I love you’ often and when they least expect it.
Send a cheeky text message at an unexpected time.
Rub things – feet, neck, back, etc. (you with your filthy thoughts!)
Hug and kiss hello and goodbye, good morning and good night.
When you’re angry, put a 5-second delay between your brain and your mouth.
Say ‘please’ and ‘thank you’.
Do things they like to do sometimes – even if it’s not your favorite.
Make the effort to remember special occasions.
Ask how their day was and really listen to the answer.
Make all big decisions together.
Don’t allow anyone to come between you.
Initiate sex – especially if you usually don’t.
Beware of falling into a rut. Shake things up a little.
Always keep dating (no matter how long you’ve been married).
Apologize to each other after a disagreement.
Accept their apology and let it go. Don’t keep a running list of misdeeds.
Treat them as your partner, not your boss or your child.
Touch feet under the covers.
Put your relationship above all else.
Keep their secrets.
Show pride in their accomplishments.
Show compassion for their weaknesses.
Play their favorite music.
Keep your expectations of yourself and your partner high, but reasonable.
Celebrate milestones (even obscure ones).
Watch each others’ back.
Compliment them to others.
Be supportive of their career.
Don’t even think about divorce unless it’s really over.
Swallow your complaints about their family.
Discuss problems outside the heat of the argument.
When times get tough, cling to each other.
Be worthy of trust.
Admit when you’re wrong.
Be self-sufficient, unless there’s a legitimate reason otherwise.
Get on the same page about money.
Don’t let the kids play you against each other.
Do at least your share of the work.
Be considerate – small niceties matter.
Take a couple’s retreat when you start to feel disconnected.
Weather the storm together.
Cook their favorite foods.
Give them a little tush pinch in the kitchen.
No name calling – ever.
When you feel wronged, say so.
Try something new together.
Encourage them to follow their dreams.
Sacrifice without begrudging.
Let them take care of you. Everyone needs to be needed.
Volunteer for a cause you both believe in.
Don’t take yourself so seriously.
Give them their space when they need it.
Remember what really matters and let go of the minutiae.
Tell them what makes you happy.
Focus on romance as much now as you did in the beginning.
Take excellent care of yourself.
Be supportive of their hobbies, even if you think they’re silly.
Get out into nature together.
Be their home base.
Anticipate what they want and do it before they ask.
Always give them the benefit of the doubt.
Get help if you need it.
Get all dolled up for them.
Have fun with other couples.
Allow them their friendships away from you.
Keep criticism fair, civil and constructive.
Make your home a haven for both of you.
Travel to new places together.
Never criticize in public.
Avoid ‘always’ and ‘never’ in an argument.
Turn off phones, e-mail, texts, etc. when you’re out together.
Be the spouse at their work functions.
Become regulars at your favorite restaurant.
Relationships take work – do the work.
If things are getting done, don’t worry about having them done your way.
Honestly believe that your relationship is going to last.
Respect their privacy.
Anything involving personal hygiene should be done in private. (Not attractive.)
Take care of them when they’re sick.
Take their side.
Cheer them up.
Cheer them on.
Remember the good times fondly and let the tough times fade.
Acknowledge out loud that your life is good thanks to them.
Golden rule – if you’re both looking out for each others’ best interests, everyone wins.
Enjoy each other!