You will probably get more suggestions from others, but the things that helped raise mine up were:
1. Exercise at a higher level than just walking. Walking (plus other factors below) took my HDL from 25 to 44 mg/dL. Running just over 20 min daily took it from 44 mg/dL to 60+ mg/dL.
2. If you have extra weight, lose it. This will benefit your TG level also.
3. Examine your diet. Your TG are elevated, which could be from excess weight or could be from a high level of carbohydrates in your diet.
4. Add fish oil and fish to your diet. EPA and DHA have been shown to be beneficial to lipid profiles.
5. Niacin (especially high doses, prescribed) do a fantastic job of raising HDL if you can withstand the flushing and if your hepatic panel doesn't show irregularities.
6. Cessation of tobacco use also will help (if you are a tobacco user).
7. If your diet contains a good amount of polyunsaturated fats, that will reduce the LDL and HDL. If you try to shift those to monounsaturated fats and keep your saturated fat intake at the same level, your LDL will stay the same (in theory) and your HDL should come up a bit.
With your low HDL and elevated TG, you won't to watch out for other risk factors associated with metabolic syndrome and the onset of type II diabetes.
If you were to be able to bring your TG down to 100 mg/dL and your other values did not budge, then you would be in the minimal risk category (<150 mg/dL total) regardless of your HDL level. However, its more complex than that so I would expect that a reduction in TG would also drop the LDL down a bit and your HDL might come up a bit.