It will be difficult especially if you are over 50. Your brain is wired for language assimilation when you are a child and that ability diminishes as you age.
That being said, the most important thing I have found is to establish a relationship with one girl and see her a couple times a week. Make a specific arrangement to teach each other the opposite language. It will be easier for her to pick up English than for you to get Chinese because she will be immersed in a foreign language and you will not be. Plus, I have found they study all the time when things are slow.
Be sure to hook up with your partner on WeChat. You will need to talk face to face daily if you really want to become conversational.
Once you have a partner, focus on mastering numbers, singular and plural personal pronouns, a set of maybe twenty verbs, and maybe 100 nouns. Basic grammatical structure will come by talking with her-it’s not really that much different than English. I found that with these few words you can construct sentences that can cover a lot of territory.
I believe that you don’t have to focus on grammatical number or tense because it seems like those things are handled with modifiers rather than changing the actual word. It also seems like you don’t need to conjugate verbs either. One verb seems to work the same for first, second, or third person. But make sure to master the numbers. From numbers you will easily derive days of the week, months, and other time related words.
You will find that there are sounds you need to master that seem, frankly, unnatural. There are a lot odd tongue positions and a lot of sounds to make with your throat. These are very hard. My advice is don’t try to use words that rely on those sounds. No one will understand you and you will get frustrated. There are plenty of work around words.
Your partner will have similar frustrations with sounds that are unnatural in Chinese, such as “R”, “L”and “th”. You can bond while practicing these sounds. There will be a lot of funny moments.
But perhaps the hardest thing to master, at least for me, is the use of the four tones. Words are pronounced in one of four tones that will completely change the meaning of the word. “Horse” and “mother” are basically the same words just said in a different tone. The word for invoice is the same as the word for idiot, with just a slight movement of the accent of a syllable. You can say some ridiculous things if you don’t master the tones. Ask your partner to practice with you. They learn the tones when they are babies.
Make flash cards and practice them every day. Google will translate the word into pinyin, which is an English depiction of the word. You can use this as a phonetic crutch on a flash card. Be careful, however, using Google Translate for learning tone and accent for a word. It is not usually correct. To learn this you will have to rely on your partner or a native speaker.
ChineseClass101.com is a good supplementary tool. The basic lessons are free and they have a convenient list of 100 important words you can link from your phone to your car radio via Bluetooth and practice while driving.
You will forget new words if you don’t use them. Keep practicing the lists. Also try to think of the word as a picture rather than a translation of an English word. If you are constantly translating in your mind from English to Chinese and back again, you will be too slow to carry a conversation. It’s hard but possible with practice.
Don’t bother with the Chinese written word, either reading or writing. You are not going to live long enough to learn it. It looks to me like a bunch of brooms chasing a house.
After saying all of the above, it has taken me a full year to barely be able to hold a rudimentary conversation at 10% of the necessary speed. Don’t give up. It is a great skill to have if you are serious about Chinese women. It is a compliment to a Chinese woman that you even attempt to communicate with her in her language. And the rewards are worth it. Trust me.