According to the Cahn-Ingold-Prelog system assign a priority to each of the following groups. (Highest priority is 1)
The keys are: 


going outwards, only look one bond at a time
look for the first point of difference
to break ties follow the chains of highest priority first


So, going out from the point of attachment, the first atom in each chain is a carbon, so we expand from there to the next three atoms in each case (in red). Draw these out in priority order (ie. highest to lowest atomic number), top to bottom. Now compare the highest priority atom on each chain, ie. C vs Cl vs Br vs C. Bromine has the highest atomic number, so this makes that whole substituent number 1 priority, chlorine is next, so that whole group is number 2 priority, the remaining two groups are a tie, so we go down their list of attached atoms, looking for the first point of difference. The second atom on each is a carbon - ie. a tie. The final atom is a hydrogen on the first group, but a carbon on the final group, so the latter has the higher overall priority. In this particular example, there is no need to go further out along the chains to determine priority order for the substituents.



So, the final priority order is: (1) -CH2Br, (2) -CHCl2, (3) -C(CH3)3, (4) -CH(CH3)CH2F