Start studying mathematical biology from basics I am really passionate about theoretical and quantitative biology and I would like to build my future career around this topic. 
I've just got my bachelor's degree in biology (ecology) but scince I've had only one math class through the years, my math skills are very poor, so I have problems in understanding even simpe models. My main interests are population dynamics, adaptive dynamics and game theoretical models of social conflicts.
I would like to improve my skills, but I have just no idea where/how to start. Could you give me some advice about textbooks or online resources?
I've seen other questions in this topic, but since I have almost no knowledge in the field of math, I am interested in resources for complete beginners. And I would also appreciate any suggestions about skills/topics I should master if I am interested in these biological phenomena.
Thank you!
 A: A lot of late nights with a sequence of basic texts in algebra, calculus, probability and statistics, and ordinary differential equations would seem to be a minimal requirement. Everyone has favorites but I think the important thing is to solve a lot of problems. 
You can find reviews of elementary texts in these areas on Amazon and elsewhere and you can usually glance at sections of the text to get a feel for the level and quality of exposition. Usually you can find something that has some mainstream acceptance and is written in a way that seems accessible. 
Personally I like Boyce and DiPrima's Elementary Differential Equations and Boundary Value Problems. Many problems in science are modeled as differential equations; but it is really important to get a good understanding of the underlying basics (calculus, algebra) first.  
You got a good suggestion for a modeling text on the BioSE site, as well as some online suggestions. The MIT open courseware site and free video lectures  from some universities can be very helpful. For specific topics you can often find class notes online that will help you work through an idea. 
If you are matriculated (or even if you are not) you should look for an academic mentor you can turn to when texts and online material don't quite get you there. 
A lot of biologists use R to deal with quantitative problems so familiarity with this can be useful. Mathematica is really versatile and there are good resources for almost any problem you might encounter. This is partly a matter of taste and experience.    
