What is the best way to cope with the loss of someone to suicide?

I'm so sorry to hear about your recent loss.  There is such a large feeling of uncertainty that befalls those of us left to sort through these emotions of such a loss, and it's never easy.  

I think it's important to remember that there is no "right" or "wrong" way to deal with loss and the "best way" for you may not be the best way for someone else.  The fact that you are aware that you are smoking more marijuana and drinking more, and the fact that you can recognize that these may not be the best coping techniques, is a very good step towards giving yourself some better support at this time.  Marijuana and drinking are type of coping techniques that can numb us to our emotions, but they do not really help us to work through those emotions. 

When it comes to grief, often one of the most helpful ways to move through the phases of grief is to use your social supports; talk to your friends and family, see your mutual friends and commiserate with each other on the loss and the uncertainty.  The more we talk about our feelings, the more we are okay with them being ours. The more we express our loss, the better we become at accepting such a loss. In talking with your supports, you may also decide ways in which you may want to remember your friend; ways you can do so on a personal level (writing a poem, planting a tree, etc.) or ways you as a group can remember and memorialize them (a special day where you get together to share your memories, starting a charity, etc.) 

We never truly "get over" our losses, but we can learnt o accept the losses and what it means to us now...but that also takes time.