A method of sizing paper produced by a papermaking process, the method comprising: adding a sizing enhancer to a fiber furnish of a papermaking process at or before a headbox of the papermaking process, wherein the sizing enhancer is a copolymer of diallylamine and acrylamide (AcAm); adding an emulsified sizing agent to the fiber furnish, wherein the emulsified sizing agent comprises a sizing agent selected from the group consisting of an alkyl ketene dimer, an alkenyl succinic anhydride, and any combination thereof, emulsified with an emulsifier polymer comprising at least one primary or secondary amine-containing monomer, wherein the emulsifier polymer comprises a copolymer of DAA and AcAm, and the emulsified sizing agent being added at or before the headbox and: after the sizing enhancer, wherein the emulsified sizing agent is added before or after screening in the papermaking process; before the sizing enhancer, wherein the emulsified sizing agent is added before or after screening and the emulsified sizing agent is added after screening; or before, after or contemporaneously with the sizing enhancer, wherein both the sizing enhancer and the emulsified sizing agent are added after screening; and making a paper product out of the fiber furnish according to a papermaking process, wherein the emulsified sizing agent is added at a dosage rate of 0.2 kg (0.5 lb) to 9.1 kg (20 lb) of the emulsified sizing agent per 907.2 kg (1 ton) of dry fiber, and the sizing enhancer is added at a dosage rate of 0.2 kg (0.5 lb) to 15.9 kg (35 lb) of the sizing enhancer per 907.2 kg (1 ton) of dry fiber; and wherein the emulsified sizing agent comprises from 0.01 weight percent to 40 weight percent of the sizing agent and 0.001 weight percent to 20 weight percent of the emulsifier polymer. adding a sizing enhancer to a fiber furnish of a papermaking process at or before a headbox of the papermaking process, wherein the sizing enhancer is a copolymer of diallylamine and acrylamide (AcAm); adding an emulsified sizing agent to the fiber furnish, wherein the emulsified sizing agent comprises a sizing agent selected from the group consisting of an alkyl ketene dimer, an alkenyl succinic anhydride, and any combination thereof, emulsified with an emulsifier polymer comprising at least one primary or secondary amine-containing monomer, wherein the emulsifier polymer comprises a copolymer of DAA and AcAm, and the emulsified sizing agent being added at or before the headbox and: after the sizing enhancer, wherein the emulsified sizing agent is added before or after screening in the papermaking process; before the sizing enhancer, wherein the emulsified sizing agent is added before or after screening and the emulsified sizing agent is added after screening; or before, after or contemporaneously with the sizing enhancer, wherein both the sizing enhancer and the emulsified sizing agent are added after screening; and after the sizing enhancer, wherein the emulsified sizing agent is added before or after screening in the papermaking process; before the sizing enhancer, wherein the emulsified sizing agent is added before or after screening and the emulsified sizing agent is added after screening; or before, after or contemporaneously with the sizing enhancer, wherein both the sizing enhancer and the emulsified sizing agent are added after screening; and making a paper product out of the fiber furnish according to a papermaking process,