I think the language you're learning Chinese in is irrelevant Kv, wether it be Spanish or English. Like some people have mentioned here, the most important thing is to get down the intonations and the pinyin, and for every word you learn to say, learn to read and write it also. It's slower, but it will make things a lot easier in the long run.

Technically it shouldn't matter. However, the reason why it may be easier to go English-Mandarin rather than Spanish-Mandarin is because there are more resources available.

I remember when I was in elementary school the first thing we learn is learning the alphabet and Chinese PinYin, which is different from English pronunciation. And then we learned characters together with their pronunciation.  

Some friends told me that a course call Pemsler makes a difference when people does not have any basic knowledge about the language he or she want to learn.

well,in my oponion,as  for a foreigner learn how to speak mandrin is easier than writing chinese characters, and the most important to pronouce it correctly is the pin'in tones. there are four tones, example: wo，third tone,means I, and i know of a podcast for foreigner to learn chinese is called chinesepod,now most of the lessons cost money, but there are some free lessons, just have a look at it, still there are some other chinese learning websites, if you need i can search some that's suitable for you.

I am a Chinese, if you really want to understand China, want to learn mandarin, we can be friends!