I get asked this question a lot at my Spanish Songs for Babies class. OK, so you're speaking one language at home, say it's English, but you learned a few words of Spanish at an evening class/GCSE/A Level years ago at school and you'd like to incorporate it into what you do at home with your baby. It seems like a great idea in principal, it's not as though your 6 week old is judging you. But the weeks pass by and the words don't come out. And then it's harder still. It feels like a barrier between you when you try and communicate in something other than your mother tongue. And English is so easy...
Well, turns out that's not unusual. Many mums (and dads) find it hard to pass on a second language to their children. There are millions of language graduates and not enough children learning a foreign language at school, so why isn't it more normal for kids to learn one at home?
The official advice is to have one parent speak only in Spanish and the other speak only in English to their children and then said child does not relegate one language to the position of being a second language and is truly bilingual. Fine. Except, if like millions of people (like me) you're not a native speaker.
I looked everywhere for advice on this and kept coming against the 100% suggestion when my first child was born. To make things more complicated my mum's first language is Catalan not Spanish so I was taught Catalan and English from birth and Spanish from about age 5. When baby #1 was born I kept wanting to say words in Catalan but my knowledge of that language is far poorer than my Spanish (which I have a degree in) so I kept backing off. Speaking only Spanish wouldn't work in my family as hubby speaks only English. SO here's what we're doing in case it helps anyone. My children are my guinea pigs... these suggestions are only tried and tested on them!

#1 Repetitive daily tasks. Learn the words for things you do like your washing routine or dressing etc. Here are a few examples
Cepillate los dientes, cepillate cepillate (Brush your teeth, brush, brush)
Cepillate el pelo, cepillate cepillate (Brush your hair, brush, brush)
Ponte la camiseta (Put on your shirt)
Ponte los pantalones (Put on your trousers)
Abrochamos el cinturon (Let's do up your seatbelt)
Sube la cremallera (Do your zip up)

#2 Accept that you are not trying to make your child fluent. That the best they may get is the knowledge that other people speak differently. And by being kind to yourself use it as a springboard to greater familiarity with the language. When your 3 year old watches Ice Age and asks you "What is sloth and mammoth in Spanish" admit you don't know. Teach him instead what is a dictionary and find the word together! Knowing mummy does not know everything is a good thing for your child, hopefully it'll show them that they need to stay curious at any age!

#3 Body parts
Again using repetition and rhythm, when putting on clothes you can say
Un brazo, dos brazos (One arm, two arms)
Una pierna, dos piernas (One leg, two legs)
Un pie, dos pies (One foot, two feet)
Other opportunities for practising your knowledge of body language comes after meal time as well as wash time
Limpiamos las manos (Let's wash your hands)
​Limpiamos los dedos (Let's wash your fingers)

#4 Instructions and commands
As they grow and your Spanish grows with them you might be able to practise your commands. In Spanish grammar you learn commands but I never had cause to use them, practically ever, until I was a parent! All exclamations start with an upside down exclamation mark in Spanish (¡)
¡Ven aquí! (Come here!)
¡Siéntate! (Sit down)
¡Ten cuidado! (Be careful!)
¡Para! (Stop!)
¡Dámelo! (Give it to me)
¡Aguántalo! (Hold (on to) it)

If you're learning the subjunctive then negative commands are the absolute best practice you can get
Come (Eat)
No comas (Don't eat)
Bebe (Drink)
No bebas (Don't drink)

#5 Songs
Obviously! There's your typical nursery rhymes of course which I use in. I also turn everyday tasks into songs. I taught J & D how to say "Vamos a..." (we're going to) in Spanish using the Here we go round the Mulberry Bush tune. As in: 
Vamos a tiny tots a tiny tots a tiny tots vamos a tiny tots a pasarlo bien (We're going to tiny tots to tiny tots to tiny tots, we're going to Tiny Tots to have some fun)
Or:
Vamos a casa a casa casa, vamos a casa... a descansar (We're going home... to have a rest)

Another good song is a little more disco. You can say: "Follow the leader leader leader, sigame!" (See Soca Boys)

#6 Donde está? (Where is)
Asking this question ¿Donde está mi coche? (where is my car) every time we've parked anywhere has taught my children a) how to say 'where is' in Spanish and b) to remember where we parked the car!

#7 Gracias and Por Favor
You can teach them to say please and thank you in Spanish but I wouldn't bother until they're saying it naturally in English. English people get cross when people don't mind their P's Q's, Spanish people don't mind in the same way as they're more direct. It's up to you but I've chosen to get them to say thank you and please for a few years before even telling them what it is in Spanish!

That's enough to get you started! Adios y hasta pronto!

 I am always looking for covert ways to sneak language learning into my boys life because otherwise they might catch onto the fact that I'm trying to teach them something. As soon as they catch me out there's only a few responses available. Either be honest: Yes I am teaching you Spanish, I taught you English too didn't I? what's the difference? Now answer me in Spanish or breakfast is off... Or there's make them laugh. If I have some energy I can be quite enterprising. The word cosquillas (Spanish for tickle) is invariable funnier than its English translation. Or I can match them huffiness for huffiness until they can't help but laugh at me. There's no point trying to retain any dignity as a mother-teacher. Asked the question (envision it spoken in super-whinge) "Why do I have to say everything in Spanish" I retort "because your mother has had 36 years to perfect being annoying. That's a lot of practice!" and grin at him maniacally. He bursts out laughing and answers the question in Spanish and in good humour.

Sometimes I resort to fairly complex games requiring preparation and thought. Like the balloon popping game we did at Spanish Club.  I drew a picture of a dinosaur and sellotaped balloons over it. No mean feat when the kids are popping said balloons... Then I had put the body parts written on small pieces of paper, one in each balloon. Finally I blue tacked safety pins under each balloon. Each child chose a different coloured bean bag (in Spanish of course) to throw at the picture. When they popped a balloon (with a great BANG!) they'd stick the name of the body part to the right bit of the picture. Thereby learning body parts such as garras - claws, dientes - teeth, estomago - belly, etc.

But the best thing I do, and by far the easiest, is leave a Spanish picture book lying around of the breakfast table so they stumble across it. And they often ask me to read it. Peppa Pig se va a Dormir (Peppa Pig Goes to Bed) is a good one at the moment as is El Gato y el Perro (The Cat and the Dog) which is all about friendship. Diez Perros en la Tienda (Ten Dogs in the Shop) is a fantastic read with plenty of repetition and great pictures. We have also enjoyed one kindle book Un Montón de Coches. Anything by Eric Carle seems to work in any language!

The trick is figuring out which books to buy. There is invariably a lack of foreign language books in even the larger libraries, especially children's books, so yes you have to buy. And I often go to Amazon for ideas and prices even though I like to compare elsewhere (eg Casa de Libros). Sometimes the same book is available for far less in euros on Amazon.es than in pounds from Amazon.co.uk, that's even when factoring in the cost of postage. And if you're not fussy, not looking for one particular title, can you can scoop up some real deals. But many kindle books don't seem to be formatted right for use in a classroom context with text spreading out wrongly and I would just pause before pressing the buy button unless you've had a recommendation (or it's super cheap!)
​
Finally, getting the little man to show off seems to be a winner. Reading a book to him and a friend or his brother and asking him questions brings out the show off in him and he can't help himself but try to answer! And despite his protestations, it turns out that the little guy has been listening to what I've been teaching him!